Me too
I also bought my foam from the Fix's and layered three plies of firm, meduim and soft NASA (Temperfoam). I glued them up and sculpted with a sanding disk. This made it possible to sculpt them to my back and legs, as well as my wife's frame. They are the most comfortable plane seats I've ever sat in. If someone is selling you pre cut seats, they 've got to cover their labor and will not put the care and materials into it. besides, a pre cut seat will be a compromise of everyone's butt out there, not yours. To me, the seats are an integral part of the man/machine interface. You build the machine, so why not spend some time on making the seats comfortable and a joy to sit in? Sure, it'll take you a few hours, but the results are worth it, expecially if you like to fly long hauls.
Foam was approx $200, then I took it over to a local hot rod car guy who covered them in the aviation fabric I provided. He charged around $300.
Art in Asheville.