Mobile Phone Unlock Codes

Hello well I'm after a site that can offer me, Free Unlock Codes for Mobile phones.

The guy at our local market charges bloody 20-30 quid.
per phone, and you see all these people at his stall all day.

I need a resource site, so I can start my own local unlocking for peoples phone just charging a mare £10- standard phone.

All help is appreciated, no spam comments if you don't know about it then please don't post.


Thanks!