07 a4 2.0t 77xxx miles on it..would it be better to buy the timing belt kit with water pump or have my mechanic buy n do everything?

 

Some shops require that they supply the parts and others let you bring the parts. Ask your mechanic. You could probably get a better price yourself unless they say they will charge you their cost for the parts with no mark up.

 

The belts on the 2.0t B7's don't have to be changed until 110,000 to 115,000 miles. The teeth on the belt and pulley's were redesigned to reduce wear and tear on the belt. The old 1.8 needed the change at 90,000 miles.