The shop i worked in briefly had a sign, $60/h; $80/h if you tried to fix it; $120/h if someone else tried to fix it
taking an image of the drive is a good idea, need a few drives hanging around to do it.
It's amazing how much crap crawls into people's computers. Make sure you equip yourself with a good sef of tools including a vacuum and an air hose (preferably outside).

You might do well to go to a local 'puter swap meet and get some 2nd hand drives to sell cheap. many people don't see the point in upgrading to a 40+ gig drive if the 2 gig was plenty big