Hi ekrolik,
Warranties only cover manufacturing defects in a mattress (which will tend to happen very early in the life of a mattress) and don’t say anything about the quality of the materials in a mattress and have very little to nothing to do with the durability or useful life of a mattress (see post #174 here). They don’t cover the loss of comfort and support that is the main reason people will need to buy a new mattress so it’s much more important to know the type and quality/durability of all the materials inside a mattress (see this article) than to use the length of a warranty as an indication of the quality of the materials or the useful life of a mattress.
The price seems to be “fair” but I would keep in mind that price is only one part of “value” and the value of a mattress purchase is always relative to the other mattresses you are considering or that are available in your area (or online for those that are also including online options in their research) so if you only have one “finalist” or don’t have other mattresses that you are using as a reference to compare with then there really isn’t any way to make any meaningful quality/value comparisons in terms of suitability, durability, or “value” regardless of the price you would be paying for the mattress.
Phoenix