If by low teens you mean £10k then you should be able to find a very tidy TD5 commercial, either pick up or hard top in that price range. But, be a little wary of the early ones - there was a problem with an oil seal that allowed the ECU to fill with oil (more of a problem on similar age Discoveries I think) - not a good move!
As Richard says a good service history is important. Plus, look for evidence of previous use - if the underside is coated in mud you're probably best to walk away - if not regularly cleaned the chassis will rot in short order. Pay particular attention to the rear cross member (it's right at the back) the back of the chassis legs themselves and what are still referred to as outriggers. Anything that is in direct line of fire of salt thrown up by tyres in winter is in for a hard time. So is the front bulkhead - bottom of the door pillars below the bottom door hinge, front of bulkhead near top door hinges and around the opening vents - all rust. Take a magnet with you...
Possibly your best bet is to talk to a specialist like Bob Hyde Land Rovers - he doesn't deal but will troll the country searching for the right motor (normally station wagons, but anything LR - non-Chelsea tractor - is fair game). That said, at present he is rebuilding the cottage, so might not be able to check anything for a while...
"avoid electric windows/air con/abs/traction control- just something to go wrong" I include Td5s in that, but they aren't as bad as many make out - just prefer to stay away form ECUs and the like. My 200Tdi will be fully rebuilt rather than changed for a newer model.
Good luck!
