AppleCare does not cover accidental damage but you probably already knew that. I would imagine the total repair cost for parts and labor to replace the bottom of the case on a MacBook Pro would be around $500. That is assuming that their is no internal damage that you are not able to see. This price is just a guess and I pulled it out of my @$$ but probably an underestimate if anything.
Yeah having the case replaced would be very expensive. I did the same thing to mine actually. I barely notice it any more though. I was actually able to get it mostly back into place with a small, soft rubber hammer my mom has; now it's mainly just scuffed.