I am using Petrol and is happy with it but everyone's choice is different.For that kind of cash you looking at a B8 model. The B8.5 maybe outside that price range.
If you choose the petrol route you will be faced with CDNC engine which is a minefield. I would not recommend it unless you do your homework.
Saying that I do have a 2009 TFSI engine and its done 2k miles before oil message appeared so can't complain.
Hopefully other petrol and diesel owners will give some views