The oil filter will cost you around Qr 75 from teyserre service centre and the oil it will all depend what type of oil u want to put (normal or synthetic) which will cost between Qr 20 and Qr 60 per litre.The 325i is a six cylinder engine so consider 6 litres of oil every change.

As far as for full service, it will vary depending on what parts need to be changed and sometimes u can find the parts outside otherwise u will need to buy it from BMW agency.

U can contact me, i know a good mechanic for bmw since I have a 318is 1992 model.

cheers