Our crib mattress was given to us by my SIL, so I didn't really do any research for one. I don't think it's very comfortable for DD so I want to get a new one, but I have no idea what makes a good mattress. I'm amazed at how much the prices and reviews vary.

So what did you look at when deciding which one to get? Is a $2-300 mattress really *that* much better than a $100 one?