I share the sentiment of many in this forum about this particular seller. Things are not liming up well. You can always do research and be savvy in buying on CL, tho. I got my 4S AT&T on the cheap last year from a buyer who was looking to unload his Christmas gift for rent money. I had him send me the IMEI and serial number, to which I ran warranty info with Apple and made sure it wasn't blacklisted with AT&T. Met him at a Starbucks with my buddy, inspect it thoroughly with my SIM, made sure the network worked, installed apps, etc. In essence, Craigslist can work for the buyer wonderfully - you just have to be savvy.
Make sure to check this out thoroughly, OP.