What I'm suggesting is that you should raise prices sharply, and just ignore anyone who this discomfits. If they think they can do it in a weekend, let them. They won't do it because pathological customers are flakes, but hey, if they were hypothetically not flakes, it is a free Internet.

There exist programmers who happily pay $50+ for ebooks. Empirically, there are enough of them to support successful businesses.

P.S. See also consulting rates, writing OSS, etc. After somebody hits my patience for free support I just quote my daily rate at them. If they don't like it, well, enjoy the code.