Parts Distributors
There are a large number of electric vehicle parts distributors accessible via the Internet. Be sure to shop around though, prices between distributors for similar products can vary greatly.
Conversion Shops
There are professional shops in many areas that will do some or all of an EV conversion for you. Be prepared to pay for the service as there is a significant amount of labor involved. You should expect prices to start around 15-to-20 thousand USD for parts and labor, more for specialty or high-end conversions.