I wouldn't spend 4k on a mattress. You can get a solid one for 1.5k tops. The important thing is doing the research beforehand, knowing what materials will last, and knowing what kind you prefer. After getting a couple of bad mattresses I got fed up and read up on it and was able to get a much better mattress because of it. Here's a site that seems to have a lot of good information. https://www.themattressunderground.com/our-articles/mattress...