Roush kit - $6, 000 after taxes, kennebell/whipple -$7, 000. This kit together you can look at $2, 500-$3, 000 if you just look. Right now on svtforum, there's is someone selling EVERY piece you need minus the department of boost manifold for $600. I'm sure you could get it for $450-500 from him. Now $1, 900 for the manifold and boom, $2, 400 roots supercharger.
If you want to make more power because you're forged, just add a smaller pullie and port the blower for a cheap, big power boost or buy a whipple head unit (fits right on the DOB manifold) and just watch the boost rack up.