I've been charging $10 for a half hour lesson for a couple of years. I live in a rural area with a limited population of around 20,000. I usually have 10 students a week. The lesson is "supposed" to be a half an hour, but I'll almost always wind up teaching for an hour. I've been thinking of raising my rates, since I'm giving extra time to the students, and my students are "used" to staying for an hour. It's a tough call though. I don't want to piss people off.