First thing....if buying from Sleep Country, etc, etc, DO NOT pay more than 50-60% of the asking price. Mattresses are the main most over priced commodity there is. No kidding. You find something you like, offer them half price. If they balk, start walking. End of the year is the best time to buy.
If you want great quality and are willing to pay, go to Parklane. They make one of the best and you have a choice of memory foam, none etc. But they don't wheel and deal. And they don't bug you while you are trying out the wares. If you have questions, you go find the salesperson. They let you browse and test as long as you like and provide the pillows. The price you see is what you pay. And they aren't cheap. But it's a great mattress. And they don't make the mattress till you order it. What's really cool is, when they deliver your mattress, they come in two trucks. One to bring the new mattress, one to haul the old one away. It's Parklane's way of insuring your new sex platform doesn't come with bed bugs and other cooties. The guy that delivers your mattress is likely the guy who made it.
And I've found that memory foam usually has Alzheimer's.....
Hope this helps....