You might have a look through this search link:
http://www.google.com/search?source...S_enUS221US222&q=craigslist+used+shifter+kart
Its going to be pretty expensive to ship a kart. You should fill out your profile with your location. It might just trigger someone to turn you on to a used shifter kart deal for sale in your area.
You should search all the craigslists ads from all the diferent towns you'd be willing to drive to pick it up. Lots of people spell go kart wrong in their ads, so when you get on C/L, do 4 separate searches using each of these 4 spellings: go kart / gokart / go cart and gocart.
I've had good luck finding all kinds of out of the ordinary stuff I wanted to purchase by posting "Wanted" ads in my local craigslist... like titled
Wanted, used shifter kart. (its free and pretty easy to post C/L ads)