there should be an audi stamp on the back of the wheel, probably on one of the spokes it its the real deal. i think a good condition set of rep rs4 wheels would go for £250 or more.
i got £175 for my rs4 reps, but they were kerbed and one of them needed repairing after i hit a large pothole. sold them with only 3 tyres and 1 alloy needing fixed.
not sure how much an OEM wheel would go for tho.