this place needs to start charging labor instead of just for parts...
while a circ may cost $45 (which by the way, is wrong, circs are costing upwards of $65 to the wholesaler and over $75 to the contractors), there's a lot more than just changing a circ. you have to drain down the system, unwire the old one, rewire the new one, fill the system, purge the air from the system, etc. that's anywhere from 1-3 hours, depending on how the system was put in originally.
if they showed labor charges instead of just a parts price, i'm sure they could keep their customers cooler