Hi brentgraciejj,
Buying a mattress on Ebay would be very risky because the odds would be very high that you are buying a used mattress or a floor model from a dealer that isn’t an authorized Tempurpedic Dealer so there would be no warranty.
There is more information about some of the things you can check for if you are considering buying a used mattress in post #2 here and if you are considering buying a mattress from a liquidator or clearance store that sells used or returned mattresses without a warranty then there is more here and here and here that I would read before considering your purchase.
Buying a used mattress or a mattress that someone else has probably returned for “unknown” reasons and that doesn’t have a warranty would certainly be a very risky choice and I would consider it to be a “buyer beware” purchase.
From the Tempurpedic warranty …
There is more information in post #9 here about the different ways that one mattress can “match” or “approximate” another one. Every layer and component in a mattress (including the cover and any quilting materials) will affect the feel and performance of every other layer and component and the mattress “as a whole” so unless you are able to find another mattress that uses exactly the same type of materials, components, cover and quilting, layer thicknesses, layer firmnesses, and overall design (which would be very unlikely) then there really isn’t a reliable way to match one mattress to another one in terms of “comfort”, firmness, and PPP (Posture and alignment, Pressure relief, and your Personal preferences) based on the specifications of the mattresses (even assuming that you can find out all the specifications you would need for both mattresses you are comparing in the first place).
Mattress manufacturers generally try to differentiate their mattress from the mattresses made by other manufacturers and don’t normally try to “match” another mattress that is made by a different manufacturer so unless a manufacturer specifically says in their description of a mattress that one of their mattresses in the same general category is specifically designed to “match” or “approximate” another one in terms of firmness or “feel” and PPP and/or they are very familiar with both mattresses and can provide reliable guidance about how they compare based on the “averages” of a larger group of people that have compared them (different people may have very different opinions about how two mattresses compare) … the only reliable way to know for certain how two mattresses would compare for you in terms of how they “feel” or in terms of firmness or PPP (regardless of anyone else’s opinions of how they compare which may be different from your own) would be based on your own careful testing or actual sleeping experience on both of them.
Having said that … if you are researching online memory foam mattresses then the mattress shopping tutorial includes a link to a list of some of the better online memory foam options I’m aware of (in the optional online step) and several of them make memory foam mattresses that they describe as being reasonable approximations of the general firmness of many of the Tempurpedic mattresses. Several of the other retailers or manufacturers that are on the list that don’t specifically describe their mattresses as being similar to one of the Tempurpedic models would probably also be able to give you more information about which of their mattress would be the closest approximation to a Tempurpedic mattress that you prefer as well.
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 (including Tempurpedic mattresses) than anyone else.
There may also be some local memory foam memory foam mattresses that may be just as suitable and just as durable but you would need to test these in person to make sure that they are just as good a “match” for you in terms of comfort, firmness, and PPP as the Tempurpedic and you would also need to make sure that they are able to provide all the information you need about all the materials and components in the mattress (see this article) so you can make sure that there are no lower quality materials or weak links that could compromise the durability and useful life of any mattress that you are considering purchasing.
If you let me know your city or zip code I’d be happy to let you know about any of the better options or possibilities I’m aware of in your area.
Phoenix