IMO, you get what you pay for. My thoughts on labor in HD diesel shops:
PM / LOF / A-B-C service- fixed prices
Brake work-$80-$100 HR
Suspension/ Steering - $100-$110 HR, $80-100 diag
Engine Diag- $120-$130 HR, $250 diag min
Electrical Diag- $130-$150 HR, $250 diag min
Same can be applied in regular automotive, just tweek the numbers.