So why don't you get on Google, and look up the value of each item?
Doesn't seem like it's rocket science....
Here, I'll save you the trouble:
Amp: 250-285
Sub: 220~ a piece.
Box: 120~
So...you're looking at around 800$.
He's not giving you a great deal, but he's not ripping you off, either. I'd say it's a pretty reasonable price. Not a "deal".