I realize this can be broken up into cosmetic/mechanical and warranty/out of pocket. So I guess we can share from all different perspectives of repair that we've had. Feel free to share about awesomely cheap repairs that you've made work as well.
I forgot to check the brakes on my truck and they wore down to metal on metal costing a good $160 for all new rotors and pads. -__-
Oh and my Dad ponied up something like $500 IIRC for a water cooled BMW X5 alternator.