Excluding market sensitive repair specials, such as "Four Cylinder Tune-Up for $59.99" 
or "Oil Change for $19.99" most of the 2000 shops we have evaluated use this formula for pricing.
  

Cost of Goods Sold (parts, chemicals, supplies, etc..) times 2 (double)
+
Labor Flat Rate multiplied by the Shop's Hourly Rate
+
Applicable Taxes, Hazardous Waste and Disposal Fees
= "Your Bill"
  

Cost of Goods Sold (Parts and Supplies):
We suggest you, the consumer, ask your mechanic the brand name and grade of the part he/she is quoting you on. Then call your local auto parts store (most likely, the same place your mechanic will be buying the parts) to price out the same parts you need for your specific repair. This will allow you to understand the mechanics same-part profit mark-up.

Shop Hourly Labor Rate:
Wow, what a big and diverse country! I Spoke with a customer today in Georgia and he charges $12.00 and hour for labor. Conversely, I know of shops in Los Angeles that routinely charge well over $90.00 an hour for labor. I suppose my point is, to know what the shop is charging you per hour to perform their labor service.