I have no idea how prevalent mattress makers are.. However, years ago we were traveling thru Texas on our way to do the Copper Canyon Tour in Mexico. We stayed for a couple of nights in El Paso where we met up with the rest of the folks on the tour. During our stay, we drove around town and saw this place that made regular and custom mattresses. We hated the mattress in our rig. Stopped by.. tried some out.. found one we really thought we would like.. but, the RV mattress was a different size than a "standard". Talked to the owner and he said "no problemo". Next day we had a custom temprapedic type mattress.. installed it and off we went for our tour.
Well, turns out that checking out a mattress and actually spending time on one are two different things. I won't go into the details.. but we didn't really like the mattress. TWO YEARS LATER we passed thru El Paso again and spoke to the owner and told him our problem. He said "No Problemo".. He took in the mattress.. and told us to try some of the other materials after we told him what we didn't like about the one he sold us. Well, we found one.. It was less "dinero" than the fancy one..
We didn't get a refund for the difference.. but.. we left without paying a "dimoero" and were happy campers from then on.
What did I learn? Couple of things about buying mattresses.. Also, mom and pop stores can be fantastic for personalized service.. and finally, if you need something custom, such as an oddly shaped mattress without paying an arm and a leg.. a small mattress manufacturer might just be the ticket.