Yes — Sigrix is a marketplace for AI agents. Creators list ready-made agents and crews there, every listing goes through review before it is published, and each one shows what it does, the model it was tested on and an estimated token cost per run before you pay. A marketplace is not the only place an agent can come from, though, and it is not always the right one. Here is where you can get an AI agent today, what each option actually sells, what to check before you buy, and what it all costs.
Where to buy AI agents, and when not to
Strip away the branding and a working agent comes from one of three places. Each sells something different, and each fits a different kind of job.
- A marketplace listing. Someone has already built the agent, tested it and written down what it does, and you buy a copy. You pay a one-time listing price, or nothing for a free one, plus the model tokens it uses whenever it runs. This is the right place when your job is one somebody has already solved well: researching a topic, triaging a queue, drafting a report.
- Your own build. You write the instructions, wire up the tools and test the edge cases yourself. There is nothing to buy, but you pay in time, and the testing is the part everyone underestimates. This is the right place when nothing listed fits your job, or when the agent is itself the thing you sell.
- A plain prompt instead of an agent. A surprising number of "agent" jobs turn out to be a single step: rewrite this, classify that, summarize the other. One tested instruction handles those in one model call per run instead of many. This is the right place for a one-off task, and the prompts marketplace sells those too.
The rest of this page is about the first option. If you are weighing it against the second, the short version is that buying skips straight to a tested result you can still adapt, while building pays off only when nothing on the market does the job. AI agent marketplaces compared works through that trade in more detail.
What an AI agent marketplace sells
"AI agent" covers more than one shape of listing, and picking the wrong shape is the most common buying mistake. These are the three you will meet on Sigrix:
| Listing | What you get |
|---|---|
| Single agents | One autonomous tool built for one repeatable job. You give it a goal; it plans the steps and hands back a finished result. |
| Crews | A manager persona above a bench of specialist task prompts, with routing rules that send each request to the right one. You chat with the manager; it answers as the specialist that fits. |
| Products | A bundle that packages a persona, skills and an assistant or agent into one listing with one price. |
Above a crew sits the AI Workforce, which composes whole crews and agents into one system that runs a complete function — the layer above a crew, not a bigger crew.
The pieces those listings are built from are for sale on their own as well: personas for a reusable voice, skills an agent loads when a task calls for them, assistants that work with you turn by turn rather than for you, and MCP servers that connect an AI to live tools and data. New to the vocabulary? The 5 AI building blocks shows how they fit together.
Whatever the shape, buying an agent or a crew gets you the instructions themselves — the persona, the prompts, the compiled setup — rather than a locked black box. You can read exactly what it will do before you rely on it, and adapt it afterwards.
How buying an AI agent works on Sigrix
- Compare on the listing page. An agent or crew page shows what it does, the model it was tested on, an estimated token count per run and any reviews buyers have left: the evidence the checklist below tells you to read.
- Add it free, or check out once. A free listing goes straight into your library, with no card needed. A paid one is a single checkout — a one-time payment, with no subscription behind it.
- Find it in your library. What you bought unlocks on its own page and in your library. A crew unlocks every building block inside it as well: the manager persona and each task prompt arrive as listings of their own, so you can use any of them separately later.
- Set it up where you work. Setup compiles an agent or crew into instructions for ChatGPT, Claude, Gemini or any other LLM platform. A crew also downloads as a bundle: the compiled prompt, plus a runnable project you start on your own machine with your own API key when the crew ships one.
- Make it yours. Fill in the variables the setup asks for, then change the text itself wherever your workflow differs from the one it was built for.
When you run it with your own key, your model provider bills the tokens each run uses directly; none of that passes through Sigrix or the seller. And if a purchase goes wrong, there is a way back: within 14 days of buying, you can ask for a refund from your order page when a listing does not do what it described, will not run, or arrived broken or incomplete. A person reviews every request. An approved refund is issued through Stripe, and your access to what you bought ends with it.
What to check before you pay
A listing is a promise, and its page is where you check it. Five things separate a solid one from a weak one:
- A run you can read. The steps the agent takes and a sample of what it produced, not just a description of the outcome. On Sigrix a crew cannot go into review without a captured test run of its current build, which becomes the sample output on its page, and an edit that changes what a live listing does sends it back to review.
- The model it was tested on. Output varies by model, so a listing should name the one it was verified against. The closer your own model is to that one, the fewer surprises.
- The token cost per run. Agents take many steps, so for anything you run often this number matters as much as the listing price.
- Scope and guardrails. A narrow agent that does one job well beats a vague one that promises everything. Look for clear limits on what it will and will not do.
- Reviews from buyers. On Sigrix, reviews come from buyers: you can only review a listing you have bought, and never your own.
How to buy an AI agent turns these into the full buyer's checklist, with a step-by-step for comparing a shortlist.
What AI agents cost
Every agent has two price tags, and a fair comparison keeps them apart.
- The listing price is what you pay the creator, once. On Sigrix an agent is either free to claim or a one-time purchase, and a paid listing costs at least $1.00 — the one pricing rule the platform enforces on agents and crews. Above that floor the seller sets the price, and it is on the card and the listing page before you check out.
- The running cost is what your model provider bills in tokens each time the agent runs. It depends on the model you choose, how long your inputs are and how many steps the agent takes, and each listing estimates it per run.
So the range runs from free listings you add to your library without a card, through agents and crews their sellers price for the depth of the job, with your model bill on top of either. Because sellers set their own prices, two agents that do similar jobs can be priced very differently, which is why the comparison belongs on what each listing shows you rather than on the number alone. To budget, multiply the estimated cost per run by how often you will run it: an agent you run every day can cost you more over a year than a pricier one you run twice.
How much does an AI agent cost? breaks down the whole stack — the listing price, the tokens, the occasional extras — and how buying compares with paying for your own build time.
FAQ
Is there a marketplace for AI agents? Yes. Sigrix is a marketplace for AI agents: creators list ready-made agents and crews, plus the prompts, personas and other building blocks they are made from, and every listing is reviewed before it is published. You compare them by what they do, the model they were tested on and their token cost per run.
Where can I find AI agents for sale? On a marketplace built for them. Sigrix lists AI agents for sale together with crews, which also have a hub for AI crews of their own. Every card and listing page shows the price, or that the listing is free to claim.
How do I decide where to buy AI agents? Match the place to the job. Buy from a marketplace when someone has already built and tested an agent for your job, build your own when nothing listed fits, and use a plain prompt when the task is a single step. On a marketplace, compare the captured run, the model, the token cost per run and the buyer reviews before you pay.
How much do AI agents cost to buy and run? Two costs. The listing price is a one-time purchase the seller sets: free to claim, or at least $1.00, with no subscription. The running cost is the tokens your model provider bills each time the agent runs, which each listing estimates per run.
What happens if an AI agent I buy does not work? You can ask for a refund. Within 14 days of purchase, request one from your order page if the listing does not do what it described, will not run, or arrived broken or incomplete. A person reviews every request.
Do marketplace AI agents work with ChatGPT and Claude? Yes. Setup compiles an agent or crew into instructions for ChatGPT, Claude, Gemini or any other LLM platform, and each listing names the model it was tested on — the one to check before you buy.
Looking for a specific agent? Start on the marketplace for AI agents. Building agents rather than buying them? How to sell AI agents covers the other side of the marketplace.
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