It’s hard to give a clear single answer since it depends on what infrastructure and cloud provider your company/team is using. All agents are straightforward to set up and can be started using the command prefect agent TYPE start --label YOUR_LABEL -k YOUR_API_KEY , where TYPE indicates one of the agent types:
You could e.g. spin up a small AWS EC2 instance with a local or docker agent to get started.
We also provide ready-made Azure resources to make it easier to deploy docker and kubernetes agents for Prefect Cloud users.
This blog post shows how to set up an agent on ECS, and ECS costs are rather low because you pay for only one container running your agent 24/7 rather than for an entire instance, and as long as you are on a free tier, this should cost you nothing.