i would go out to the junk yard if possible. i know the pull-a-parts in the southeast let you have the rear end for around 100 dollars, and it includes the brakes, pretty much anything attached. if you go the junk yard route you could save a LOT of money, but possibly one that isn't in good condition.
guess you'll just have to check out the miles... good luck with it, i'd give you mine from my explorer, but i'm not sure when i'll be taking it out.