That, I believe, is the vent without the scoop. Add on whatever the scoop might be worth.
$800 seems very reasonable to me for everything in that kit. Of course you are paying for the little STi on the inside of the scoop. But I don't think he's out of line at all.
Quick related question:
I went to the Rallispec web site and those are stated as being for the '02-'07WRX. Does anyone have experience installing these in a pre-'01?