Hi vettehigh,
I took a quick look around Binghamton, NY and there are few if any good choices that are within reasonable driving distance in terms of either local manufacturers or better outlets that sell mattresses that have good value. (NOTE: see post #2 here for the better “possibilities” I’m aware of in the area).
This of course means that your best option is likely to be an online purchase.
There are really two directions to go with this. The first is to buy a mattress which is either “good” or “not good” and if it isn’t good then the outlet offers a refund which costs you little to nothing. In other words the price of making a mistake is very low.
The second option is to buy a mattress which can be “adjusted” after you get it so that if you make a mistake then the parts of the mattress that are “good” can be kept and the parts that are “not good” can be either changed or exchanged.
Both ways it would make sense to get as close as possible based on your needs and preferences because regardless of the cost … exchanging a whole mattress or even a layer of a mattress takes some effort and thought and is certainly an inconvenience at best.
So to improve the odds … it makes sense that your height and weight and sleeping positions are taken into account … and in this case especially your sleeping positions.
Side and stomach sleepers are the most difficult combination because the needs of side and stomach sleeping are completely opposite. Side sleeping needs thicker and softer comfort layers because there are more pointy parts (hips, shoulders, and pelvic crest) or pressure points which need pressure relief. Stomach sleeping on the other hand is the “flattest” sleeping position and the primary challenge for stomach sleepers is to have a firm enough support layer to prevent the much heavier pelvis from sinking into the mattress too deeply and creating a hammock effect and likely back issues and pain. Pressure relief is a secondary issue because the weight is already spread out over a much larger surface area so the comfort layers on the top need to be as thin and firm as possible. When someone is a combination sleeper then the thinnest firmest comfort layer that provides adequate pressure relief on the side is the best choice. A range of about 3-4" of softer material would be typical for a side sleeper and closer to 3" would be better than 4". Under this should be as firm as practical.
So since all memory foam is soft in terms of it’s ability to bear weight and provide support (you will always sink more deeply into any memory foam over time than a more elastic and resilient foam like latex or polyfoam) … I would likely be looking at 3" of memory foam over a 6" or so support layer of suitable polyfoam. Your weight and height works in your favor here as well because people who are taller and slimmer can use thinner comfort layers than those who are heavier and larger framed. Other things that may be important when you are looking at memory foam are the importance of free movement and the importance of temperature (how hot you tend to sleep).
So if I was looking at option 1 (a mattress that may work but that I can get a full refund at little to no cost if I was wrong) … then I would probably be looking at a place like Costco, WalMart, or Sams Club which offer full refunds. Sams Club at the moment for example has 2 mattresses which use 4 lb Aerus memory foam (10" and 12") which may be close to what you are looking for. Aerus comes in different levels of density/quality but is very breathable and a little faster reacting than other memory foams (less movement restricting and more breathable and cooler). 4 lbs which means that it is “in the middle” in terms of it’s durability. A mattress with 5 lb Aerus memory foam would cost more but would last longer. This is a good compromise and the prices at Sams Club are very good and there is no real cost in case it doesn’t work out. I would avoid the 3 lb Aerus (or any 3 lb memory foam)
If I was going to go with option #2, I would choose an outlet like the few that are mentioned in post #12 here. All of these offer good quality and value in their price range and several have varying degrees of ability to customize your choices at low cost either before or after purchase through layer exchanges.
King size all latex with a foundation and including shipping would be more than your budget but a latex hybrid (latex comfort layer and an innerspring or polyfoam support core) is still in your range. A very good option for this would be here. These mattresses have 3" of talalay over a 2.35 lb polyfoam base (high quality) and 1.5" of polyfoam in the quilting (which is just a little over the inch I usually recommend as a maximum but because the quilting compresses it and also because of the great value of these mattresses I would not make this an issue). They also offer a choice of ILD in the latex layer. I know the manufacturer of these well and think highly of them and once they make a few changes to their main site to bring it up to date they will be listed as manufacturing members here.
So hopefully this will help. I would spend a little time talking to the outlets I’ve listed here and in the other thread to get a sense of who offers the options, knowledge, service, and value that are the most important parts of your personal “value equation” and make your decision from there. All of these will be higher quality and much better value than what you would have available locally.
Phoenix