Cripes, you gotta be careful these days haven't you!!! Scary!
I've generally always bought cars from our local dealer or ask them to find a me a car. Since they have been responsible for maintaining and servicing they know I will continue to give them my business, I know they make some money on the sale but they have never let me down yet.
Buying at auction, for me, no chance. I just would not do it. Doesn't matter how cheap it is.
It is best to buy from a half decent looking car dealer, maybe a VW or VAG specialist, and have some piece of mind, and pay the premium for it.
With even minor components costing big money on some cars these days, you have to be very careful.
In summary then, find a VW dealer nearby, tell them what you want, let them find it, and pay for a warranty.