have to agree i have a 2008 86,000 on the clock which started @ £12,000 but dealer over a few months dropped to £10,000 which i snapped up for £8,000 with £2,000 px on my old car, in good condition and good spec these cars seem to hold their asking price.
for a c7 avant for 10k you will be looking at 100,000 plus on the clock easy, lower the mileage higher the price
i also have the auto gearbox 3l tdi and as of now have had no issues with it the 3l engines also come with the chain belt not the cam belt in the 2l versions to the best of my knowledge