Arent superchargers (in general) more expensive than turbos? At least last I priced them..
If the turbo for the smart is $4k, I'd hate to see a supercharger, unless the smart breaks that rule.... of which I wouldn't doubt.
Oh and don't forget to take the level of psi from the turbo for limits to save ya the trouble... I forget what it was.
Either way, it would be a good second option.