$50 will last you a good long time if you don't use many tokens, and you are judicious about which model you use, and don't need web search much.

However, on a fixed price plan your behavior changes. It's a qualitative change in how you work, rather than quantitative. Ideation and product design and specification start becoming bottlenecks.

I started out the API route. I started spending $100 a month once I was spending upawards of $10 in tokens a session.