I repair iPods and have replaced clickwheels on iPods (as well as iPod video's) before.
I just got done modding my iPod and put in a white clickwheel for a black iPod (silly, I know).
The clickwheel part is something like $20 and I charge $30 to put it in and that $30 also covers return shipping. Hopefully it's just your clickwheel and not the actual motherboard (unlike previous generations of ipods, some of the clickwheel is built into the motherboard)
my ebay feedback is 100% and is under ifixipodsfast
if you want a more personable way to get ahold of me send me an email to firstname.lastname@example.org
Also, what color is your ipod's clickwheel?