Ask HN: How to find good beta users

Dear HN, I developed an app that uses substantial computing ressources and thus I cannot afford to simply have an open, yes not even a closed beta in the common sense of the word. Nonetheless I'm looking for some users that would take the app out for a ride without breaking the bank.

So my question to you is, how do you find quality beta users without the need to prescreen a large quantity? (That would be impossible as I'm a single dev)