I work two jobs, and both are tutoring. I tutor for my university in a free tutoring center (I'm paid) for one, and I private tutor for the other. I charge $35/hr. If someone is in dire need, I can always adjust and work with them though, so I might charge them $25/hr instead. If they really cannot pay, I always recommend the drop in tutoring center I work at.
You guys seem really low for how much you guys charge. Around here, if you have an undergrad degree you can charge anywhere from 30-40/hr, if you have a masters you can charge 40-60/hr, and if you have your doctorate you can charge anywhere from 50-100/hr...