Sports tickets on Craigslist?

I'm interested in buying premium tickets for a major sports event, and have looked in various places, including Craigslist. I found extremely good tickets for what appears to be about $200 less than similar tickets I have seen elsewhere. The seller offers tickets to every game of the season in quantities of up to 10 and is only contactable by phone (area code is familiar). How wary should I be of this type of deal?