I purchased my Kawi Mule...pristine condition from a local guy via Craisglist a couple years back.
I think if you vet the seller by asking the right questions and are looking at legitl pics it can prove successful.
My Mule was previously owned by an older gentlemen that has purchased the Mule new for he and his father to hunt out of. Unfortunately, his father passed away right after he bought the Mule and it sat in his garage for a year until he decided to part ways with it.
I also bought my KTM 350XCF-W via Craigslist and it was also pristine with low hours.
This website has an aggregation feature that pulls ads from Craiglist and Ebay, etc from all over the country if you are willing to look outside your immediate market.
http://www.quadhunter.com/kawasaki-mules-for-sale