It's not just the LLM costs, to keep your agents busy you need to move them of your workstation onto a server/cloud. I currently have about 16 claude code agents working on different bugs, uses so much resources that my macbook pro m5 max becomes slow to respond. Using cloud session would free up my macbook for other work.
Anthropic recently handed out free cloud resources (it's still free, guess they want you to get used to the fact that cloud is not free). I went through $250 cloud budget in less than 2 days.
Feels almost as expensive as LLM calls.