If you are going to buy a sander, I have a hog sander, its like a da but its sanding disk is geared so when you press on it while your sanding the pad will keep spinning, (it doesnt spin fast like a disk grinder so you wont grind into metal, but it removes bondo and paint pretty fast. ingersoll rand makes a pretty good one.
http://cgi.ebay.com/ebaymotors/Ingersoll...=item53e03f662f