Save or spend: Spend
This decision comes down mostly to comfort, but it's safe to say that the cheapest mattresses don't have much padding (you'll feel the springs), are made with polyester (which can pack down over time), and have fewer coils (you want at least 350).As you go up in price, you gain layers of support, like body-molding memory foam or the "Posturepedic innerspring" featured in this Sealy.
Tip: Ask the salespeople to start you from the bottom up, or they'll have you test the priciest one first - and let you convince yourself that nothing less will do.
