As Don & Lori indicated, any bed store would be happy sell/ deliver/ install/ remove the old one.
But is there something more? Is your coach one that has a somewhat smaller nonstandard bed? Is that perhaps your concern? If so, some folks have somehow managed to live with a standard mattress on the smaller platform.
Before you spend the $$ on (what we consider) an overpriced, name brand mattress, I encourage you step back for a moment. We had Tempur-Pedics for years before going full-time and wanted the same on board.
But before we shelled out another $2k+, we tried a cheap $200 memory foam mattress I spotted at Aldi. It was great! So good, in fact, I went back many times to buy another to store as a spare--but we've never seen them again.
We replaced it after 5 years with another that we love, Signature Sleep Memoir 8 Inch Memory Foam Mattress with CertiPUR-US certified foam, Queen. All of $155. Just not a fancy brand name.
Al & Cindy
'08 Discovery 40X Cummins 350 ISB 6.7 - '16 Lincoln MKX
Full-timing since 2014 after 35 years in Rockwall TX - Home base now in Kerrville TX