I'm new to the GTI world, but in my research for a DSG on Autotrader etc, there seemed to be very few sub 35,000 mile cars out there. One dealer car that I was monitoring in Leicestershire had a 2006 GTI with 33,000 miles, not many options, up at £8500 before Christmas 2015. It's still up for sale now, but the dealer has upped the asking to £10,000.
The limited edition ones certainly seem rare and at a further premium.