It's so very easy to spend far more on a car than it's really worth in the open market !
But the cost of maintenance often does this in itself ................. and therefore it's usually better to find a car where that cost has already been absorbed by someone else.
Heaven forbid that you should have a nasty ( or even a very minor ) collision or otherwise insurance claim, which would be a write-off for the car and I would guess a pay-out in the high £'00s alone,
Provided you're happy with this potential then go4it, it's ever so nice driving a good looking and robust Mk3 that's 18 old and that will probably last you for many years to come and give you superb, reliable, safe motoring.
Malc ( I bought mine in June 2011 for £1400 with 126000 miles and full Lexus service history, recent cambelt change etc ) and in superb nick )