i use 3 Funk Audio 18.0 subwoofers in my Home Theater room. these are big boy subwoofers, and have outstanding performance.
the Funk 18.0E is right at $3k and essentially the same subwoofer.
https://www.funkaudio.ca/store/p13/Funk_Audio_-_18.0E.html
a step up or two over the two listed. hand made including the drivers. the extension, articulation, and build quality is on another level. yes, a little more money, and you do have to get in line for delivery. this is the good stuff.
Nathan Funk was a pleasure to deal with.
highly recommended.
https://www.funkaudio.ca/store/p1/Funk_Audio_-_18.0.html