They are priced against the actual model pricing exposed by OpenAI and the rest.
With some surplus, obviously, that I keep.
The best info I can give is my own "bill" as a user since August 5 2023 when it got live. Purchased 40 USD, spent 26.
That's 26 USD in almost 22 months of usage, and I use it pretty much, for coding and what not.
Your mileage may vary but we're talking just over 1USD per month :)
