We bought it from a local independent dealer. The store had the air bed also as well as things like a few hospital beds and the like. It's sorta like a therapeutic bed store
Anyway, I don't think I would have bought it online - although my mom bought a memory foam bed from QVC and she just loves it. I knew that if we didn't like it and wanted to return it, there would be no problems with a local dealer - but we wouldn't give it up for the world!!!
There's nothing special that you need, everything fits, just like a regular bed - we did put a special waterproof mattress cover on it (it's not like plastic - it's hard to explain - it looks like cloth, but is waterproof) because we have 2 dogs in bed with us and although they've never peed on the bed, they have occasionally thrown up!!!
Regular bed sheets should fit it just fine. We do have to have special sheets, but only because we got the adjustable frame where the head and foot raises, so we have a split king mattress (I didn't want to have to sleep raised up just because my husband needed/wanted to sleep with the head of the bed raised and visa versa) - so we have 2 twin extra long mattresses to make a split king sized bed, and the sheets are hard to find. We use a regular king size top sheet - so we always have to buy the sheets separately. Similarly, we had to buy twin XL waterproof mattress covers - but the store where we bought the bed, sold the covers.