How much will VW dealer charge me for changing a seal on cooler in 2002 Cabrio?

My cooler is leaking oil like crazy-my friend looked at it and said it's a seal or something. I want to know how much a dealership would charge me for a repair. I need a guide line to know how much I should pay my friend for it-most likely he will do it for free and I want to be fair. Plus I don't want to wait with it until Monday. Thanks for your help!How much will VW dealer charge me for changing a seal on cooler in 2002 Cabrio?this is a very simple fix. aside from buying him the part, just give him a case of beer or $20.