Cost of putting in double glazing?

I am looking for a rough quote for double glazing for flat I am moving to at end of march. It's an upper cottage flat and measurements as follows lounge ; 206cm across x 170cm drop; bedroom 138cm x 170cm then 3 rooms approx 103cm x 170 cm. I just want an idea of how much to put by. I want cheapest white PVC turn and tilt. Thanks