On a Jetta or a Golf, it has to be 2003+ (generally speaking). Anything newer and you run a far better chance of having issues than after. Problem is, any Golf/Jetta worth getting that's 2003+ is going to run a fair bit closer to $10K... But of course, that depends on how popular they are where you are. They're all over here, but they hold their value because of the die-hard VW fans.
Generally speaking a Jetta/Golf or Passat (you can go a little older on those) will be fairly bullet-proof with the VR6 and the TipTronic. Try to avoid the 1.8T before 2003 as they're known to have sludge issues... And if you are looking at one, doesn't matter what engine/transmission/trim level... Make sure you can see the repair history. The cars get a little picky when they aren't given enough attention.
Just a bit of opinion:
A Passat of similar vintage will probably hold together a bit better than a Jetta or Golf of the same time. Its bigger, costs a little less to insure (as I recall), and is quite comfortable.