Most phones will display their IMEI if you key in *#06# (no idea if iPhones play nice, it would be fairly typical of Apple to do it differently). Other than that most physically have their IMEI printed behind the battery cover and often again as a sticker on the packaging.
They do play nice with *#06#![]()
iPhone has IMEI printed on the simcard holder, however these are easily damaged and its not uncommon for a OEM simcard holder to be used....still wont tell you if its been stolen or not...
I would be very surprised if you can get a new iPhone for £300. :O
yeh the massive market bay has them new for £400.£50 more would bag him a new 8GB 3G.