The 2.0 in the Jetta is a decent unit, but a wee bit low on power (not a bad thing for a youngster). VWs are stoutly built, and will keep you safe, no question. I know people who have had about 200,000 miles out of one of those engines, with proper maintenance they should be reliable. I'm sure that Ben could add more from the technician's point of view.
You can expect pricing to be in the region of around $15k or so for a Certified Pre-Owned 2013 model year Jetta SE with about 30k from a dealer, a couple of grand or so less for the Jetta S. Make sure that the car has had the voluntary recall performed for the steering wheel clock spring, without which the dealer should not be able to deliver a car.
Privately you'll pay a little less but won't have the peace of mind of the factory extended warranty, and you will need to take the car in for that recall yourself.
CarMax are no-negotiating (as are many other dealers, ours included) but they are always more expensive, which is why you will never see CarMax on Cars.com or Autotrader...