To each his own...but I am with BigNasty, WHY?
If you are dissatisfied with the power of your 351, chances are it wont handle a supercharger.
I have a fresh 351, forged pistons .030 over, roller conversion, 272 comp cam, 1.7 roller rockers, GT 40X heads... the basics for a supercharger, and it gets down right scary at 4500 RPM, so I nixed the thought of a blower.
Your stock E4OD diffinately wont handle the increased torque.
But if you want to go for it...$1700-$4500, depending on what you want.