Tempurpedic

[Life]

I've heard many good things about them so im looking to get one, they have a pretty big line of mattresses all the way from $700 to 5k, anyone have an opinion on how noticeably different they are? If I get one of the least expensive ones will I be missing out on alot?

also do most people get the mattresses and then just put them on top of their old foundations or box springs? this is what i plan to do but tempurpedic reccomends against this.