Hi ok11,
The first place I would start your research is the mattress shopping tutorial here which has all the basic information, steps, and guidelines that you will need to make the best possible choices … and know how and why to avoid the worst ones.
Once you reach step 3 and are ready to start testing mattresses … then the better options and possibilities I’m aware of in the Washington DC area (subject to following all the steps in the tutorial post of course) are listed in post #2 here.
While this mattress uses high quality materials … I would be very cautious about spending $5000 on a mattress as well … especially if you are ordering it online and can’t test it in person. These are more specialty mattresses that I would generally suggest testing extensively in person to make sure they are a good match for you in terms of PPP (Posture and alignment, Pressure relief, Personal preferences) and if for some reason I did order it online as a blind purchase then I would make sure that there was a great return policy so that you an use your sleeping experience to test the mattress without risk. If I was spending this much on a mattress I would make some very careful comparisons because I would need to have a compelling reason to justify the higher cost. It would need to be clear to me that there was nothing in a lower budget range that would be a suitable choice and I would need to be confident that the higher cost was “worth it” based on specific criteria that were important to me and that weren’t available in lower budget ranges.
Phoenix