There's actually a ridiculously cheap ForkenSwift-style Fiero conversion being documented on DIY electric car right now. It's on the road:
ELECTROFIRE - Fiero + forklift components - DIY Electric Car Forums
He even started out at 48v (brave for a car of that weight), but eventually upped it to 72ish, I think. 72 seems to be the minimum the "normal" crazy EV converters are willing to tolerate.
Net cost is roughly $1k, I think.