Get what ever one you like, as long as it is a diesel... Do not worry about the mileage on any diesel under 100,000 miles. You will be much better in the long run with a diesel car. Alot of people don't understand or take into account the the "less" maintenance that is needed on a diesel engine, with a diesel, change the oil and filter (most times oil change time is 2x longer then gas), change air and fuel filters when needed (when told to in the manual, not when you feel like it) and that is it, as long as the body/suspension holds up the care will last almost for ever, hell you don't even have to worry about coolant hoses on a diesel like you do a gas, way less heat under the hood to break down the upper of the hoses... Another thing when looking at what car with a diesel, don't worry about horse power, torque is what matters, torque is what gets you moving, HP is what makes you go "Faster" on the top end.
FYI... When you go to look at this diesel and pull the oil dipstick, the oil will look like crap, even if they said they just changed it, no worries, that is how it should look, you want it to drip off the stick, not stick there on it, if it sticks, then the oil has not been changed when it should have been (engine full of shit, for lack of a better word), if that is the case pass on that car and and go look at another... Oil is the "cleaning" fluid of a diesel and it gets full of carbon, that is why most have a bigger oil filters then gas or some even have 2 oil filters and most take a few more qts of oil in the pan (example, same car, 4qts gas, 6qts diesel).