I have been researching this housing for our school district and found that Apple is the place to go for me.
If it is the "chip", "cracked", "dirty,filthy hand rests" - the part#922-7754 is the replacement, '''Version2'''. This one is for the macbooks that were Early/Late 2006. You can get one of the original housings except that it will continue to crack, get dirty, etc...
'''Version 2''' is the better housing for your macbook. Because I work for the schools we get an education price. I guess googling 922-7754 or eBay you may find something in your price range. I would buy from iFixit except they do not carry the quantity I need (50+). I would however use their guide to install. Very good for old girls like me to put computers back together. Good luck!