I asked a question a little while ago at a small stackexchange satellite site. It got a few upvotes but no responses. I used as much bounty as I could to feature it. It still got no responses. I was a bit bummed they didn't refund the reputation, but whatever.

I am quite confident that a working professional could give me an excellent answer in about 2 minutes, and I have to say subjectively the question is pretty interesting (not a "how do I <x>" or "do my homework" question). It is unusually hard to Google, Wikipedia doesn't have the right information, and there's only one major enthusiast forum that might have users that know the thing. I'd be willing to pay a token amount, maybe $20, to get the answer. Not that I think $20 is worth getting out of bed for, but given you were already using a Sunday afternoon to answer a few questions, not a bad minutely wage.

I think my main concern is that such a site is likely to become essentially micro-projects, more "do this for me" than "answer my question". And I think people who are paying would be even angrier than usual if their question gets moderated away for doing this.