Online memory foam mattresses have become a bit of a commodity and the biggest distinguishing factor between them appears to be the marketing (and legal) budget.
I did not want to pay 2k$ for a good mattress because it is just a stupid rectangle of foam. Each time I read about how they have nasa engineers in their teams to help them innovate on 'mattress technology' I choke up a little. How can somebody write that with a straight face ?
I ended up buying one on amazon (a Zinus if anybody is interested, heard about it in another HN thread)
Mattresses truly are a weird one though. You can see how overpriced they are by the mere existence of these massive stores with allegedly-valuable inventory, that are always empty, because people don't need new mattresses that often!
Of course, they're ridiculously overpriced so you can get great "deals" on them as they're always running tax-free sales, etc.
Thankfully when my wife and I went to try out mattresses for our fancy new big wood bedframe, in the process of trying everything from $600 up to $3000+ (california king size pricing), she declared the cheapest one her favorite, and that was that!
Basically, mattress stores are cheap to open and print money. This is also why there are so many nail salons