yep. duck and run....
there are really only 3 ways to establish uniformity.
1- find a reliable EC and use him. Don't beat him over the head for every nickle and dime. Don't get multiple quotes on simple projects. Let him make money and make sure it's a two way street (that he doesn't look to kill you either) A good symbiotic relationship goes a long way.
2- put everything out to bid with full drawings and spec sheets. This way all prices are apples to apples.
3- have a list of do's and don'ts. No MC. EMT only. etc. This is the hardest way to do it. You spend more time meeting with different contractors to explain your rules than they do performing the work.
As a contractor, I prefer option 1. If i know that you are not constantly looking for a cheaper price, I'll give you everything i have and then some.
