Hi Beachin,
Welcome to the Mattress Forum! I like the dancing cat. 
There’s nothing wrong with buying something when it is truly “on sale”, but the important thing is to note the difference between “on sale” and “for sale”. The problem is that most mattress “sales” are really marketing gimmicks where the “regular price” is manipulated in order to make the advertised “discount” look more substantial. This video explains how most mattress “sales” really work. Honest retailers rarely offer large discounts, as they promote pricing that is competitive on a daily basis, so their sales events tend to be smaller percentage discounts. And remember, a low price on a low-quality item isn’t a deal. It just means you’re paying less for something that is still an inappropriate product. English author John Ruskin once said, “When you pay too much, you lose a little money – that is all. But when you pay too little, you sometimes lose everything, because the thing you bought was incapable of doing the thing it was bought to do.”
A warranty in and of itself has absolutely no relationship to the useful comfort life of a mattress, so that would be one of the less important things to consider when purchasing a mattress. The more important thing is knowing the quality of materials within the mattress. It appears that this item requires a payment of $50.99 to get a warranty on the mattress.
[quote]
I’m posting the link here and I posted the details/ material below… Your input would be greatly appreciated.
Select Luxury Medium Firm 14-inch Cal King-size Memory Foam Mattress
www.overstock.com/Home-Garden/Select-Lux...5977719/product.html[/quote]
I would need to know the density of the 10" polyfoam base layer and the density of the 1.75" polyfoam transition layer as well to be able to make any meaningful comments about it in terms of the quality and durability of the materials in the mattress. We already know that the top 2" or memory foam is only 3 lb. in density which is a lower quality memory foam, which would already put this in a category of items I would recommend that people avoid, even more so if you’re in a higher BMI range.
The Overstock customer service reps also aren’t very knowledgeable about “matching” their mattresses to different body types and sleeping styles or about the type and quality of the materials in their mattresses so it may be difficult to get accurate information from them. They are generally the type of business that will sell you anything that they can convince you to buy. They also don’t have any exchange or return options on their mattresses so if the choice you make doesn’t turn out to be as suitable for you to sleep on as you hoped for in terms of comfort, firmness, or PPP (Posture and alignment, Pressure relief, and your own Personal preferences) you won’t be able to exchange or return the mattress. The options you have after a purchase to exchange or return a mattress (or in some cases the individual layers of a mattress) can be an important part of the “value” of an online purchase.
You said that you’ve been doing a lot of reading, so I’m assuming that you’ve read the mattress shopping tutorial here but two of the most important links in the tutorial that I would especially make sure you’ve read are post #2 here which has more about the different ways to choose a suitable mattress (either locally or online) that is the best “match” for you in terms of “comfort”, firmness, and PPP that can help you assess and minimize the risks of making a choice that doesn’t turn out as well as you hoped for and post #13 here which has more about the most important parts of the “value” of a mattress purchase which can help you make more meaningful quality/value comparisons between mattresses in terms of suitability (how well you will sleep), durability (how long you will sleep well), and the overall value of a mattress compared to your other finalists based on all the parts of your personal value equation that are most important to you (including the price of course and the options you have available after a purchase if your choice doesn’t turn out as well as you hoped for).
When you can’t test a mattress in person then the most reliable source of guidance is always a more detailed phone conversation with a knowledgeable and experienced retailer or manufacturer that has your best interests at heart and who can help “talk you through” the specifics of their mattresses and the properties and “feel” of the materials they are using (fast or slow response, resilience, firmness etc.) and the options they have available that may be the best “match” for you based on the information you provide them, any local testing you have done or mattresses you have slept on and liked or other mattresses you are considering that they are familiar with, and the “averages” of other customers that are similar to you. They will know more about “matching” their specific mattress designs and firmness levels to different body types, sleeping positions, and preferences (or to other mattresses that they are familiar with) than anyone else.
Their detailed knowledge of their mattresses and how they fit with different body types and sleeping positions along with your feedback from local testing, a customer base of many people that they can use as reference points, and any exchange, return, or any options they have available to customize a mattress after a purchase can help lower the risk of an online purchase. These online retailers or manufacturers can also be a good “value reference” for local purchases to make sure that if you are paying a “premium” for a local purchase (in exchange for the kind of “in person” guidance, service, and value that comes with dealing with a local retailer that can help you make more “accurate” choices that you have tested in person) is not too high.
If you’re looking online (and it sounds like you are), use the experience and expertise of the members listed in post #21 here who are all very experienced and knowledgeable and specialize in providing the type of help and guidance on the phone that can help you make good choices. There are a wide range of latex and memory foam and other options included in the choices there and I believe that all of them compete well with the best in the industry in terms of their quality, value, service, and transparency.
I know that you’re working with a tight budget, so for those that have a more restricted budget then post #4 here and the posts it links to include many of the better lower budget online options I’m aware of as well.
I hope that information is helpful to you.
Phoenix