Just Bought one of these, some advice,for that money i'd want it perfect so
1.) Check for rattles and knocks,likely front arms or arb bushes/links.
2.) Check Cambelt and water pump have been changed, it will be overdue for it's second belt.
3.) Make sure the brakes are good as they can form a lip on the inside of the disc which is not visable
4.) Check that the car reaches operating temperature of 90 degrees and stays there,stuck thermostats seem very common.
5.) Give the car a good test drive and check for any code's flashing up ,dreaded "motor control system failure"
6.) Make sure the clutch and DMF have been changed , if driven kindly it should be changed around 130k,potential £1000 bill.
7.) Tend to get some rust above windscreen and just before rear arches and has been stated rear floor pans.
1.9JTD 16V is a gem of a motor , obviously make sure it has been serviced regularly especially oil changes.
Pricewise depends what has been done, if it has all of the above recently done then not too bad. Please let us know how you get on.