I think William hit the nail on the head.
Most of us are probably old enough to remember when auto mechanics time was charged out at $45 - 50 per hour. Since then the rate has steadily climbed, and I think I read somewhere that the average is now between $100 - $150 per hour, depending on the dealership and the specialty.
You can sometimes do better if you find someone who is operating independent of a dealership, but you run the risk that they may not be experienced with the specific make/model of car you have.
When I bought my 1987 Toyota MR2 the next purchase I made was the "Green Book", which is the big service manual sold to the dealerships for use by their service techs that outlines step by step procedures for most service jobs. This goes WAY beyond what a Chiltons or other aftermarket book provides. I used it to do some service work that would otherwise have been beyond my abilities.
Anyway, the point is the higher rates are likely to involve people time more than parts costs.