Sometimes if you go to the smaller, family-run mattress stores, they will have floor models that have just come off display due to new product arrivals. My roommate got a queen size mattress and boxspring for less than 500, including delivery and removal of the old mattress. The other stores were going to charge her 1200 for the same bed! Go in there and tell them what you want, what kind of sleeper you are, and what your price range is. And make sure you go to several different stores, look in the sales fliers and bring them with you when you go.
Also don’t try too many beds in one store. (A good salesperson won’t make you do this because they should be able to tell by the information you give them what might work best for you.) You’ll start to mix them all up, kind of like when you go into a candle store and they all start to smell the same after a while.
Beds and sleeping are very personal things. So you should really gather as much information as possible before making a large purchase.
Hope this helps.