As a big dude and a side sleeper, a good mattress is hard to find. I don't remember exactly which one it is but we have a Purple that we paid around $2000 for a couple years ago, and it blows every traditional mattress I've used out of the water. It is exactly the right combination of softness to prevent pressure points on the hip and firmness to prevent the kinked back from a crooked spine and I'm getting the best sleep I've gotten since my 20s.
We bought it skeptically, and I was pretty sure I was going to use the return policy and get something cheaper. I did not use the return policy. If I had to replace it now and had to spend $4000 to do it, I'd do it, and I am a cheap bastard.. I'd bitch and moan and kvetch the whole time, but I'd do it.