We have a Comforpedic and I've told you about it in a different post. However, it cost a lot of money and I know people can't afford it.
My in-laws bought a bed from Sleep Design (the Mimi) that is a VERY comfortable bed. I believe they only bought the top mattress (I could be wrong, though) and it cost around $600. The Sleep Design website isn't very good, but you can call them to get the name of dealers in your area.