My car stalled when I was braking at a stop light. What is wrong/cost to fix?

First off when it is cranking it is turning over. You had a crank and no start condition. Any cel? I suspect a fuel delivery problem. Have the fuel pressure and volume tested under idle and load conditions by a qualified tech.

On both the 4 and 6 cylinder engine I have seen the idle air control motor on the under side of the throttle body get dirty and stick causing the engine to be lean on start up, or stall particularly on cold running conditions. Does the engine otherwise run smooth and have adequate power? I would also look for vacuum leak particularly at the air induction boot between the air filter housing and throttle housing, look for cracks in the air boot pleats.