Andy,
I bought mine on Ebay. Look for matress toppers and you can get like a queen or king size 2 or 3" thick memory foam for a good deal. Just gotta look carefully as some will sell for 200 bucks and then you can find one for 80 or less. The company I got mine from sold iregulars for 50 bucks and it was just like a corner that wasn't 3" and the rest was perfect. Good luck. Here to save you time. http://shop.ebay.com/items/__mattres..._scZ1QQ_sopZ15

Marty