The price seems pretty good to me. I would not buy one unless it had some maintenance records. I service the 3.6 a lot and overall it is not a bad engine. The early ones (2006) had some oil pump issues, but from what I've seen those have all been sorted out by now. I have seen the occasional cam adjusters get sludged up and cause some timing chain issues, but those are from people being idiots and not maintaining them properly, like from infrequent oil changes as well as poor quality engine oil. The transmission and rear end is pretty much bulletproof. I have seen some valvebody issues but I am pretty sure that one will still have a warranty extension. If it has a bad one, you will feel a harsh shift between first and second gear usually. I think its a good buy and one of these will most likely replace my fiance's 01 V6 4motion.
I couldn't tell from the pictures (no interior shots? WTF?), but I'd try to find one that has the sport seats, they are so much better than the standard seats. If you have a bad back like me, they are a must. I also noticed in the underhood shot that the dipstick tube looks bent off towards the driver's side. That looks a little weird.
Normal maintenance is pretty much on par with the rest of VW's lineup. Nothing too major or costly if you are somewhat mechanically inclined.
I say go for it! Good luck