Will - I haven't seen Select Comfort beds at discount so far, but they do offer sales once in a while. They mostly sell through stores in local malls so you can (hopefully) easily try before you buy.
At the time (early 2002), our king size model 4000 bed above cost something like $2700 including box spring, delivery, setup, and IIRC a comforter. So it was definitely not a cheap purchase.
The model 4000 is only one or two steps up from their low end. The higher end models had fancier controls (nice but not needed) and thicker pillowtops. I think a quieter pump was also available. We found the thicker pillowtops actually took away from the feeling of changing firmness; i.e. they detracted from the experience instead of enhancing it. A quieter pump would be nice but we normally make adjustments while awake so in the end it's not that big of a deal.
The box springs are different than you find with 'normal' mattresses. Basically they have to be hard surfaces. You could use a normal box spring and lay a sheet of 1/2" or thicker plywood on it to provide the required rigidness if you want to save the $ their box spring costs. We were moving from queen to king so we needed them anyway. (The box spring itself is really just a plastic box. Just a frame with a hard top & a fabric cover to make it match the mattress.)
The whole king size mattress weighs probably less than 25-30 pounds and can be safely folded while partially deflated to maneuver it around corners and such if need be. The top zips off and can be separately washed (or replaced with a thicker pillowtop or whatever). No flipping, of course.
The warranty is something like 15 or 20 years on the mattress & 5 on the air pump. The pump is external and sits under the bed.
One great thing is that I like a softer mattress than my wife, so our sides are at different firmness levels. And if you've done some unusual exercises lately, you can always adjust the mattress temporarily to provide a softer/firmer surface while you 'recover'. Very flexible.
When I made the purchase, there were other air mattress suppliers who had cheaper offerings. But the warranties generally weren't as good and most used vinyl instead of rubber for the air bladders. SelectComfort seemed to have the best rep and they were the only ones who only made beds. The other manufacturers made air beds in addition to exercise equipment, etc. I've no idea how the market is now.
I've never had a bed that showed up in a few mid-sized boxes before.
I'll ditto mubs' comments on memory foam.
