Chirp (HD) gives you $30 per 1M characters for free on the free tier also
One other feature I'd really like: Having the AI figure out who is saying what and use different voices (e.g. one voice for overall narrator, and separate voices for each person who is quoted in the article).
Not sure if any of the solutions out there do that automatically without my guidance.
(Still probably wouldn't pay more than $2/mo for it - I just don't use it often enough to justify paying much).
And, you know, this is not a service I'd provide others. Just for my own use running from my PC. Audible won't know or care, just as no one cares if you borrow a book from the library and photocopy it for your own use.