The kind that saves you money. ;)

Joking aside, a quality mattress can last for decades (and will often have a manufacturer's guarantee of such). The price of the mattress is surprisingly non-correlated with the annual cost of ownership:

http://www.us-mattress.com/durability.html

Simmons World Class and above. I used to pooh-pooh a nice mattress but years of sleeping in horrible hotel foam beds ruined my back.

So while it may cost more, a good mattress is definitely worth the money.

talalay latex