lmold, I was talking to people in Austin, TX about airguns, nobody(I talked to) thought that airguns can be so powerful - which just tells me one thing, there is not enough marketing, so people simply are not aware about it, so no interest, no sells, no places to fill airguns, blah-blah. Before I got my compressor, I was not seriously tuning my rifles, just because I was afraid to spend too much air and there would 5-6 hours of intense manual pumping workout to fill air tank again.
However, thinking about using my compressor to get some money back - it sounds like a terrible idea. Even for $10. It would limit me to stay at home while compressor is feeling somebodies air tank, also there are ways to make a lot more than $10 while tank is being filled. Literally, you can make more trading stocks manually on a stock market than filling somebodies air tank. Of course, it is a risk and requires some specific knowledge.