Include the city you live in, your age, whether or not you're single, and how much you tip (if any).
When I lived in Eugene, I could get a good haircut for $15-16...20 bucks with tip. They served me a beer during. Now I live in Portland, which is apparently a big enough city that I have to pay $25-30, tip not included, for anything decent. I'm not gonna go to SportClips or whatever--if I wanted a crappy haircut I'd do it myself for free. I'm 30 and single so I gotta at least look presentable.