Kenny runs an off-premise golf cart rental business called Tee Time Golf Cart Rental. His rates are very competitive compared to Disney's. If you search back or look at old posts over pages 2,3,4 etc. You will find more cart rental info. Many people on this board have used Kenny and he has superior customer service.
Another off-site vendor is Steve Senesi who's business I recall was linked to a post about 2 weeks ago. Steve has 6-passenger carts as well as 4-passenger whereas Kenny is exclusively 4.
Bama ED
PS - no website for Kenny but rates are approx $35/day for a week long rental. Longer rentals get lower average daily rates. Compare that to Disney's $60 plus per day