Hi Zerbert,
Mattress warranties come from the manufacturer that makes the mattress not from the retailer that sells them so the mattresses they sell would still have a warranty although you wouldn’t have a local retailer to act as an intermediary with a warranty claim so you would need to deal directly with the manufacturer.
I would also keep in mind that mattress warranties only cover defects in a mattress which are relatively rare and generally happen in the first year or so of the life of a mattress and they have little to do with the durability or useful life of a mattress or how long it will maintain it’s comfort and support before you need to replace it. The most reliable way to assess the durability and useful life of a mattress is by making sure that you can find out the type and quality/durability of the materials inside it (see this article) and making sure that they meet the quality/durability guidelines here. There is more about mattress warranties in post #174 here.
They are a fairly new business but some of their mattresses may be worth considering.
As you probably know from your reading here and the information in the mattress shopping tutorial (and the guidelines here) I would avoid the major brands such as Simmons, Sealy, and Serta and it’s also very unlikely that you will be able to find out the quality and durability of the materials inside most Spring Air mattresses so you would be safer to avoid them as well (unless you are dealing with a particularly knowledgeable retailer that can provide you with the information you need to make an informed choice).
The mLily mattresses are made in China so there would be some additional risk or uncertainty involved with them as well (see post #6 here) but some of them may be worth considering if you can confirm that they meet the quality/durability guidelines I linked.
The odds are higher that you will be able to find out the type and quality of the materials in any of the Sleep Design mattresses they carry and based on my conversations with Stan the owner they are much more transparent about the materials they use in their mattresses so they would certainly be worth considering … again assuming that the retailer you are dealing with can provide you with the information you need to confirm that there aren’t any lower quality materials or weak links in any of their specific mattresses you are considering.
There is also more information about the 3 most important parts of the “value” of a mattress purchase in post #13 here 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 suitability, durability, and all the other 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 to fine tune the mattress or any exchange/return options that are available to you).
Phoenix