Mario - One Custom Homes and Remodels we charge our normal rates, especially as these are normally more complex jobs that your security companies and electricians can't/don't want to do.

However, on more simple rough-in jobs, espeically where we are ONLY doing the rough-in, I've definitely had to be very competitive at times, offerening basically bulk rates as drops (1-5 drops = $125ea, 6-10=$115 ea, etc). This is a bit more of a gamble which sometimes pays off and others times doesn't. i've only "lost" money once, but because it was me doing the work I really just lost time. Every other has either came out fine or with just a slightly smaller profit margin than usuall. The gamble is that I will get the Final System sale and installation as well. 

I see it sort of as marketing. It gets me more face time with another contractor that I can try to make look good as well as the client.