That class documentary about Barcelona, where they showed most/all of their players are on performance related pay. The biggest example was Edgar Davids. Im not sure on the %'s and figure but it was something al the lines of Davids agent wanted £60k per week
Barca wanted to offer £40k per week, £10k for an appearance, £5k for a win, £5k a goal/assist
Davids wouldnt sign the contract, and ended up at Inter Milan, then Spurs.