I paid £500 for my 2002 Dci 65 (95k miles) only reason it was so cheap was because it had a couple of issues, one of which costing £260 to fix, the other issue is with an airbag light where the previous owner hit some ice, smacked a curb and the airbag in the passenger seat deployed and the pre-tensioners on the front and rear passenger seatbelts fired.... Getting that lot sorted won't be cheap as need ecu reconfiguration after having new airbag controller, new pre-tensioners and seatbelts fitted, the controller being the more expensive part out of the lot.
So there are some cheaper ones out there but as others have said, be prepared for problems (I've been very VERY lucky with my find I think)