perished seal on base of passenger window on 2005 B7

[woodbine77]

Has anyone else experienced this problem? I only noticed it when I saw a little bit of condensation on the inside of the window when it had been raining. The seal i'm referring to is at the base of the front passenger window, found between the metal strip and the glass. My pollen filter has been changed two months ago, so I have ruled this out as the possible cause.

I'm sensing i'm going to be fleeced by Audi and would be grateful if anyone could say whether its a job that can be done at home, after buying the part from Audi?

Does anyone know how much such seals cost and the time needed to fit them, and the level of difficulty?

Thanks