Hi rob2121,
The most important part of a mattress purchase is how well it matches your unique needs and preferences in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences). A mattress that works well for one person may be completely unsuitable for someone else to sleep on. TheNXG 575 was never a good value option IMO and while I personally liked the “feel” of a thin layer of quilted latex over the memory foam, it’s certainly not a mattress I would have considered buying.
I would also be very cautious about buying a mattress on ebay from a seller that doesn’t offer a return privilege and that is selling a mattress that is most likely used or a return. If you buy a mattress that isn’t a good match for you in terms of PPP and you can’t sleep well on it then no matter what the price or “value” of the mattress it would have very little value to you.
I would be very cautious about buying any major brand mattress where you aren’t able to find out the quality of the materials inside it (see this article). They tend to use lower quality/density materials and even if a particular mattress in a showroom is a good match for you in terms of PPP … if it has lower quality foams in the comfort layers then they will soften and break down prematurely and you can lose the comfort and support which is the reason you purchased it (and the loss of comfort and support isn’t covered by a warranty). A mattress that works well at first but then doesn’t last you a reasonable length of time before you cross the threshold from sleeping well on it to “tolerating” it relative to the price you paid would also have little value for most people.
Some of the better options and possibilities I’m aware of in Connecticut are listed in post #2 here and the posts it links to.
I think TandL’s thread here may be the one you are looking for.
Phoenix