Using W202/203/210/126 from last 2 years. No problem so far.
Oil Change 5.5L - I'm using Mobil 1 in it. 6,500/-. Changed after every 6,000kms - 7,000kms. My car is 35,000kms driven.
Air Filter - 1,800 (Genuine). Change at 3rd Oil Change.
Oil Filter - 700 - 1,000 (depends from where i buy). At every oil change.
Mechanics are easily available other than Shahnawaz.
Things i got changed when i bought car.
Transmission fluid - 17,000.
Power Steering Fluid - 1,000.
Engine V-Belt - 3,800.
Only problem my W202 gave me was with AMF (Air Mass Flow) Sensor. My driver washed it's engine with water and AMF Sensor got damaged (Own fault).
Link to my W202 Mercedes Benz C180
Keeping in mind your budget i only shared Maintenance cost of W202. Options you have are W202 (1993 - 1999) & W124 (1988 - 1995). You will get nice W202 60,000kms - 80,000kms between 1,150,000 - 1,250,000 (depending on options & Trim). Make sure you don't get car with after market AC. Car should have noiseless suspension. Full service history will be a cherry on top :). Almost every time car driven on Hi-Octanne, only use Premium when Hi-Octanne isn't available. In my opinion best buy will be W124 E280/230. Why, W124 is not computerized that make it's almost zero Maintenance than W202. Options are better Electric seats, Memory seats etc. Driving pleasure is better. And, E280 is better in fuel as compared to W202. Me and my friends once went to Multan on 1994 E280 86,000kms driven and it took around 21 liters of Petrol.
BMW E36 is easily available in your range. Out class condition low mileage BMW E36 will be between 850,000 - 1,000,000 (I hope no one pops up & claiming my price is wrong as i already bought and sold two 1997 BMWs E36 318i, bought for 865,000 & 940,000 both were bought from PakWheels 6 - 10 month back).