Looking to purchase BMW 3 series

[DaveyA]

I currently drive a VW Bora but i'm looking to change to a cheaper car where i have no finance, I have a budget of around £3k and have been drawn by the looks of the BMW 3 series.
The cars i have been looking at are 1998-2000 318 models with betweeen 60k - 80k on them.
What sort of things should i be looking out for with these cars?
What are the price of parts like compared to say an audi or vw?
Also what sort mpg would i expect from the 318?

Any help much appreciated

[DaveyA]

What is it actually about the car that is expensive?
The service costs or the amount of fuel it drinks.
I've only had my bora about a year but with having to change the camblet and water pump and a 50k service, it came to about 400 quid. Is that a similar price for the BMW?