Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
So my friends Macbook Pro Charger broke and he was wondering if this one would work as a replacement or not ( http://www.ebay.com/itm/321704284791 ). He has a 15" 2011 version.

I wouldn't bother, Apple still sells the originals; teardown's of some third party chargers, like this, have shown them to be downright dangerous. Spend the extra ££/$$/€€ and get a proper one, it will prevent fires, damaged equipment or even, god forbid, death/injury.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.