[Chkysbak]

Ok, so I have removed the old spring mattress from the sofa bed, and have placed a 3" memory foam pad down and trimmed to size (48x72). I was wondering if anyone had any idea of where I could get an air mattress that is 48x72 (3/4 Full). I have searched almost everywhere but I don't want to spend $300 on an air mattress. I was just looking for a cheap one, that I could use as we don't use that bed much and it would just add a little more comfort. Of course if I can't find one, I will just go to Wal-mart and get a 5" memory foam and trim it down. Any Ideas?