I'm looking to buy a pre-chipped Wii, but where can I get one, and how much should I expect to pay?

thats a huge rip off

Yea, in reality it's not THAT expensive considering the return you make on the games themselves.
Especially if you never owned a GC, quite a few gems there you can nab as well.
It's kind of funny, Wii modding is one of the few things where being an early adopter is somewhat beneficial.