2. How much would you be willing to pay for it (0 is a valid answer)
Say I'm making an app that lets you chat with Freddy Krueger via a mix of GPT-4 qnd 3.5. I want my API keys on a server so users can't decompile it. While I'm doing that, I might as well hide all my prompts on the server.
Then I'd like to track which users are using it the most and bill them accordingly. A typical arrangement is to maybe allow the player to reload $10 on Google/App Store and charge them $0.06 for using some functions, and track that credit amount in a database. Or I might charge $1 for a bunch of uses, like a single playthrough.
Can I build this? Sure, but it'll take a few days and I want to focus my energy on just doing the front end stuff, the game, or whatever service.
Since I could build it, I wouldn't pay too much for it. And eventually I want to migrate off it to save money.
It's useful for scaffolding early on, as I try to make $5000/month and know whether it's worth investing more energy into. If it's cheap, fast, and reliable, I may never move off it, just like how I'm stuck on Heroku. It's just cheaper than hiring someone to handle this. If I'm worried about vendor lock in, I'll migrate sooner than later.
Early on, I'll be making $0 and so I'd be willing to pay very little. That's where many similar options fail, they charge you $50 per month or so regardless of how many tokens you use, which is a total waste when I'm using less than $1.
That's not a good question to ask developers. Most of them undervalue software (because they're capable of building it themselves) and will give you a "cup of coffee and a donut" $ figure, when the actual market might pay $100s or $1000s per month.