When I went to buy a mattress, I discovered a whole, sleezy world out there. Why do people make fun of used car salesman when mattress salesman are so much worse?
Then I found Better Bilt Furniture. A no-frills warehouse hidden at the northern base on Queen Anne (near SPU & Fremont bridge). I bought a fantastically comfortable mattress for about a tenth of the price charged by those sleazy chain stores.
When you walk into Better Bilt, expect them to just let you wander. They are so opposed to the hard sell, that they will probably ignore you completely until you ask someone for assistance. It is a refreshing change.
They sell all kinds of furniture, upholstery, mattresses, carpeting, etc.