Convinced that online ad for iPhone is my stolen phone?

Hi, so my phone got stolen two days ago. I deactivated my phone so that they can't use it and was in the process of looking for a new phone when I stumbled upon an add on my local kijiji where they are selling a white iPhone 4s 16 GB (the exact same as my phone) unlocked to my carrier. Although it is quite vague of a description and can be anyone's phone, I'm almost convinced that this is my phone but I don't want to email the person directly asking them. What is the best approach? I was thinking of notifying the police (Don't know if they'd do anything about it), bringing my phone box with the serial number and a few people with me in case of confrontation. Or is it better not to bother? Please leave me feedback on the best approach or what you would do if you were in my situation

Bring one big guy with you and take your serial.number and check it, he shouldnt have a problem with it if its his but i don't think they would sell it like that. If i stole your phone i would sell it at a pawn shop or something i wouldnt risk selling it to ppl face to face