Why are there mattress stores on every corner? Because there is huge margins in it. Lots of $10K bed buyers out there!
I'm lucky I don't have back or sleep issues, so I really don't get spending big bucks on a bed. The most important thing is to find the right sleep style for you, not to buy the most expensive bed.
My favorite bed of all time was a soft-sided, tube-style water bed I bought because I couldn't afford a real bed at the time . Just like a sleep number, without the cost.