You can get a refurbished one for as low as $1600: http://store.apple.com/us/product/FC975LL/A
That's how I got mine. It's obviously not the latest model (I also got a 2012 rMBP in 2013 and I have no regrets about it). I haven't run Win 8 through it, but I can tell you, it's a fantastic computer.