Never used 1-800 mattress, but have bought from:
US-Mattress: Mattresses from Sealy, Simmons, Serta, Stearns & Foster
They have every major brand, every level quality and deliver and set up at your home. However you have to do your research and know the different levels of quality each brand has and test the mattress in a store. One problem is most manufacturers have 4 or 5 different names for the exact same mattress. So look at things like coil count, layers of different materials and firmness ratings to make sure what you test and what you buy is the same. If you do your homework you can get significant savings ordering online from them.