http://www.racesystems.com/cobra
As far as cost of my cobra blower kit...not counting the head unit, it cost me about $400 to have the plates water-jet cut, time and materials.
I spent about 60 hours design time, and cut the spacer stock on a lathe myself 10hrs.
I'm working now on another bracket kit like this for the 385 series that accomodates all the usual accessories. It's for the fox body mustang; I doubt it will fit in a cobra. I could probably design one for just alternator and power steering and make it fit.