I've never given lessons, so take this with a grain of salt, but this is what I've seen browsing ICC vendors and various other coaches.
NM and below: $20-$30 for a random NM, but an established teacher can charge more. Dan Heisman is something like $80 or $85, I can't remember.
IM and FM: $30-$50, the range depending on how well-known they are
GM: $50-$75
Famous teacher (Kaidanov, Heisman, etc): $75+
The figures above are just ballpark estimates, of course it will vary from person to person. Plus, the stuff above is based on online lessons. Everyone charges considerably more for in person lessons to factor in travel time. Here are some links that might give you an idea.
Kaidanov -
http://www.kaidanov.org/lessons.html
Heisman -
http://danheisman.home.comcast.net/~...hess_Fees.html
Sam Shankland -
http://www.samshankland.com/Services.htm
Akobian -
http://akobian.com/lessons/
Here is a link to coaches of all levels on chess.com that might help you come up with a rate also.
http://www.chess.com/coaches