just had clutch replaced and shocks and springs upfront and airbags at rear all within the last month, bearing in mind that it almost has 98K on the clock and all of the stuff that has been replaced was oringinal then I dont think that they are expensive to maintain, regular oil changes are the key but then you would do that with a normal car, everything else is wear and tear, just make sure all previous owners are not farmers.
I have had my 2001 TD5 for nearly 3 years and may be looking after christmas for one on an 04 or 54 plate, so choose wisley and it will pay you back. ps get it re mapped though, turns it into the car it should have been !!!