Hi cheesepuff,
The most effective method of finding the best quality and value mattress for you is in this post. This will link you to the basic information you need about mattress materials and construction so you can ask better and more informed questions when you are mattress shopping and perhaps more importantly help you connect with the better factory direct manufacturers and sleep shops that are in your area (or online). It will also give you a reference point so you can tell who is giving you factual information and who is just passing along the latest marketing story.
Who you work with when you choose (or design) a mattress can be one of the most important parts of buying a great mattress. Randomly testing mattresses made by major brands or sold in mass market outlets will waste a lot of time but none of these will generally have the quality or value of a factory direct manufacturer or smaller independent manufacturers that are sold at better sleep shops. There are many choices where you can custom build a mattress of many types (and many of the members here and other across the country do just that) but their knowledge, experience, and ability to give you good guidance is an important part of how likely you are to end up with the best possible choice.
Some preliminary research, choosing who you work with, and eliminating your worst choices are good steps to take before you even begin to test mattresses.
There is no mattress or “formula” that is right for everyone and since each person is unique, the mattress that is best for you is the one that provides you with the best PPP (Pressure relief, Posture and alignment, and Personal preferences), uses the highest quality materials available in your budget range, and best fits your “value equation”. There is much more about this in the overviews and in post #2 here.
$4000 is more than you will need to buy an absolutely amazing mattress and I usually suggest that once you are over $3000 (queen mattress only or the equivalent in King) that you begin to ask why you are looking at mattresses in this price range. While there may be reasons that are important to you … I would hope that you know specifically why you are choosing a mattress in this budget range when there are so many exceptional quality and even custom mattresses available for less.
I would put Aireloom (made by Kluft yes) in the “major brand” or “low value” category that would be one of the choices I would eliminate right off the bat in most cases. I would include Macy’s in the list of retailers that I would eliminate as well. The mattress you linked has 3" of cheap polyfoam in the upper layers along with some “high loft fibers” that will compress and more polyfoam a little lower down. I certainly wouldn’t consider this as a good quality/value option at the prices they charge. This thread may be of some interest regarding Aireloom.
So I would spend some time reading through the links in the post I referenced and then choose some better local manufacturers or sleep shops to work with and then begin looking at mattresses with a little different perspective and knowledge about what really makes a good quality and value mattress 
Phoenix