$4750 is what you can expect to spend with a compressor, that is comparable to other twin screw supercharger kits being produced today. It is not cheap, but these are all low volume fabricated parts for a market whose sales volume will likely be low. I can't justify tooling up to have things cast for the predicted volumes this community will buy, so it drives the prices up compared to higher volume solutions.
Compared to other power adder kits, keep in mind you won't have to buy (or can sell $$)- Filter, CAI, TB, Intake, and fuel rails. That's over $1k in hardware easy. You buy this kit, and some exhaust, and everything "bolt on" is finished.