My box spring is broken and my mattress is a piece of crap with a big sinkhole right in the middle. I have some money saved up and I'd like a new mattress/box spring combo. I'm looking at around a 500 dollar budget. Any recommendations? I've never bought one of these before, so I have no idea where to start. I know there are all these big mattress superstores, but I don't know if they are any good or not as far as pricing is concerned.

Just to be clear, I'm looking for a Queen sized mattress and box spring combo.