Sign up for the API and use the playground. You don't get the plugins, but you pay per usage. GPT-3.5 is super cheap, and even GPT-4 isn't that expensive. My first month, when I had only access to GPT-3.5, I didn't even break $1.00; and now that I've gotten access to GPT-4, I'm at about $3. I've only once had it tell me that it was too busy for the request; I tried again 30 seconds later and it worked.