To sum it up: "Mattress stores have low overhead, low labor costs and higher-than-usual profit margins, Sam Woods said, Senior Vice President of Sales and Operations for Mattress Firm.
“If you sold three or four beds a day, and your average ticket is $1,000, that’s a $4,000 day, times 365. All of a sudden you’ve got more than a million-dollar business there,” he said."
"Consumer Reports puts gross profit margins on mattresses at 30 to 40 percent, both for wholesalers and for retailers, and up to 50 percent for makers of super-luxe products."
http://www.straightdope.com/columns/read/3265/why-are-there-...
My last two beds have been from either Costco or Sam's Club. No high pressure sales, less bullshit, and better pricing. The one time my wife and I went to a mattress store, we paid probably 30% more than the warehouse club prices and the bed's springs went bad years earlier than expected.
I highly recommend avoiding mattress stores.
http://www.themattressunderground.com has lots of good info if you're in the market. Casper and the rest aren't bad deals, but there is better / different stuff out there without the terrible mattress store business model.
Brand-name: Dr. Pepper
Off-brand: Dr. Perky
Unbranded/Generic: "Soda" in a white can