I'm looking for a 12" bottom casing that is in good shape.

My bottom casing, i mean the peice that supports the battery, latch, all input ports, all 4 corners of the computer, etc.  Like this..

http://www.ifixit.com/cart/catalog/product_430_G4_Aluminum_12_1_133_15_GHz_Lower_Case.html

Not looking to spend too much..  Let me know..