You'll run into injector, pump, and DMF/clutch issues on pretty much all common rail diesels. They aren't always 'known faults', but more 'fucking expensive service items'.

Often it's best to not get the lowest mileage one as the chances are it's not been through the 'expensive consumables' yet. I'd rather buy a 120K Mondeo TDCI that had had a pump, injectors and DMF in its life, than a 60K one that hadn't!

For 5K I'd be looking at an ST TDCI, but then I'm a Mondeo-bummer!