Not a lot of used scooters for sale around campus. You could try the local classifieds.
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There are shops on the French side, with prices ranging from $3500 and up. I get my mechanical work done at the Kawasaki dealership (on the way to Cole Bay). They cost a little more (especially with the bad exchange rate), but they do a good job. People's Insurance is on campus this week to talk about insurance and registration, since I'm not as familiar with the process.
Good luck!
UCLA, Engineering (2006)
AUC, Medicine (2013)