Keith and I haven't bought a mattress in a long time, but we do have a pillowtop. I always regretted buying it. It's an Eastern King, meaning that it's six inches longer than a California King, and it's always been difficult to find sheets for it. For years now, I've bought them when we go to Phoenix to visit Keith's brother and his wife. And yes, sheets are expensive, always were. It's a mystery to me why mfgrs haven't kept up with the size changes.
And speaking of size changes, furntiure these days is huge! I plan to have my family room sofa reupholstered for yet a fourth time, because I can't find a sofa to fit the space. Designers seems to think we all live in palaces.