Beware, folks. Buying a mattress is tricky business. The mattress industry was, and in my opinion still is, at about the same level of openness as a used car lot on the wrong side of the tracks. Many years ago, maybe the 1970s, the government looked into the industry, may have been the FTC, I can't remember that far back for sure. But the bottom line was you could not compare mattress prices between stores because one mattress might be sold under a dozen, maybe it was dozens, of series names. A $600 mattress under one name at one store might sell for $300 elsewhere under another name.
I recall my father having one custom made, a king, harder on one side than another, at a manufacturer in his city around 1980. Standard mattresses like his special one ran around a thousand dollars before discounts back then. He paid around a hundred dollars. Maybe that explains why for years there were almost as many mattress stores as gas stations!
That's one reason I prefer air mattresses. My base is known! If the bladders are high quality and the topping is decent, I've got a known quantity. Even there, prices can be ridiculous, but that's within my control if I keep in mind its guts is just air.
While there has almost certainly been some consolidation and improvement over the years, I doubt the situation is all that much better, reading the advertisements.
Mattress "experts" should correct me where I'm wrong.
'11 Eagle 320RLDS
'02 F350 PSD Dually 4WD
DW's Ride, '13 Expedition