Craigslist iphone unlock service?

Hi, I found someone on craigslist who is offering to unlock my iphone by getting my imei number for $10. He wants me to pay $5 before the unlock, and $5 after.
He says he will send me a file when it's done, and when I connect my phone, it will be done.

Does anyone have experience doing something like this from an unknown source?
I mean, it's just $5, so i'm not too worried about it, does it seem trustworthy?

http://newyork.craigslist.org/...79248.html

That is SCAM! There's no unlocking by file! The only option is a factory unlock! You will never see your $5 again.