I read through the links regarding tips on negotiating the best price for a mattress snd I have a question. Is it better to ask/state about a discount before or after the salesperson gives me a price. For example, when I ask him for the best price should I tell him that I don't need a boxspring or ask him about discounts (being a student, return customer, coupon, etc) after or before the quote? Also, in regards to price, I have a sleep train 15% off coupon from sleep train. Would they object in any way after they quote me their best price to use the coupon? So far I have only dealt with sleep train dealers but i still intend to look elsewhere as well. Any feedback would be appreciated. Thanks.

Try the coupon after you've made your best deal, but probably they won't honor it, they'll say, no that's 15% off the RETAIL price...
Your best bet, in my opinion is to get quotes on the net or other stores and then use those to talk them down to a cheaper price. Be prepared to walk out, and walk. If you don't find it cheaper you can still come back for that price. Ask him for his best price, THEN tell him you don't want the box spring... Sometimes they'll tell you that you really need it but in most cases you don't. Tell them you have a platform and are putting it on a platform with solid wooden slats - completely flat with no curve.
Don't buy a bed with a pillow top, unless that pillow top is latex. Otherwise "pillowtop" is another way of saying "We've put a whole bunch of cheap pu foam on top that is going to break down quickly and hurt your back." Instead get a FIRM mattress then put your own high quality memory foam (not the cheap stuff) or latex on top of it. That way when it breaks down you can easily replace it.

Fubu,

The best advice I can give you from the other side is to be serious about making your purchase. Look the RSA in the eye and tell him/her in no uncertain terms that you ARE buying a mattress today (and mean it). If an RSA knows he/she will get a purchase from you, he/she will be far more willing to go out on a limb for your business.

Mattress prices vary wildly by region but for the most part are marked at about 50% margin. Few retailers will go below 40% even to save a deal so use that for your negotiating points. If you're buying a Simmons World Class Queen Mattress only I would shoot for about $950-$1050. In my area I would consider that a good deal.

-Alex