There is no totally correct listing of prices beyond Disney's prices on their site (for those that have a specific price). The non-Disney sites are only updated when they get updated menus, and sometimes not all that often. Even on the phone, I think Disney gives only a range for the buffets most of the time.
Maybe if you listed which particular ones you are interested in, and when you're going (since peak dates affect the prices), people here could tell you what they recently paid.