Amazon has the Segway Ninebot 12V Electric GoKart Powered Ride-On Drift Kit for $648 with free shipping. 

Attaches to the Ninebot S or S MAX *(not included)* to make a fully-functional GoKart with a 13.7 miles max range and 10 mph speed (reviewers are reporting up to 24mph with the Ninebot X max).