In a wobbly economy, small cost differences start to matter. In Pittsburgh, the gap between city and suburban tax rates has become large enough to redirect buyer behavior, and agents working across Allegheny County are watching demand shift accordingly. The city of Pittsburgh levies a 3% local income tax and a 5% transfer tax on real estate transactions, according to Janette Schafer, a real estate agent with Coldwell Banker Realty in the Pittsburgh market. In surrounding suburbs, those figures drop to 1% and 1 to 2%, respectively. The transfer tax is typically split evenly between buyer and seller. During the...