Not sure about the price on the rears, but it's 67.78 + VAT for the drivers side one and they don't come painted, they are gray though so if someone wasn't paying attention it might just get put on the car!
Mine wouldn't come off at all, screws all knackered, ended up basically ripping it off and then drilling the screws out! I didn't have any signs of rust along the bottom of the door though!
JoJo - did you paint yours yourself or get it done as I'm thinking of having a go if Audi can get the paint?