I picked up a 5400 for $320 shipped, used but nearly brand new (still had that new electronics smell), off a private seller...
I was at the right place and right time though...
Anyway, I've owned 4 receivers, 2 amps, 2 integrated amps myself, and have installed 3 for family. So far, so good. I've also bought a lot of stuff from AC4L, and I highly recommend them as well.
Congrats and great choice!