I bought a Yamaha DGX 600, I think It's called, and it was about $1000 or so, it records 5 layers to each track I think, and it has 500+ different voices as well as P.A.T. (Performance Assistant Technology)
It's a really good keyboard.
As for realistic, the keys are weighted, lighter at the top and heavier at the bottom to get the realistic feel of the piano.