Shame having a thread without a reference to the "real" electric charger:
Boosthead.com: Pricing
Old kit... if I recall right, three custom-wound electric motors running about 15 horsepower... some 6-7 psi of boost. The current kits use a centrifugal supercharger and range between 10-18 hp... the 10 hp variant does about 5 psi of boost. Between $2-$3k... which is cheap... the original kit was around $4-5k ten years ago... which would mean $6-8k now.