Damn, after reading all the responses I have just figured out how to make this work...
Yes you can offer "free" pre wire to a builder. But, like most things in life, there is a catch. First, depending on size and value, you need to determine how much wire and labour you are willing to risk. 6 phone and coax, 4 data and 4 rooms of audio?? or something like that. Next, the "free" is only available to pre construction buyers. Those buyers must then sit through a 90 min. "seminar" with your sales staff explaining all the wonderful things they can have in their new home, and or add to their mortgage (the big upsale).
If you can't get almost every client to buy something, even an upgrade or more locations, then your doing something wrong.
Even to move a couple of jacks could cost a few hundred dollars (you just recouped cost)
As for the builder, if he has some lots that will be built before they are sold, give him the lowest possible price you can for those. As long as it's not more than 30% of the homes in the development, remember, these will eventually get sold to people that you may never meet.
2 big problems with this. 1. find a builder that likes this and the terms. 2. this is geared to homes 1/2 mil or less, those people are often spending everything they have just to get the house, you are a luxury item. Thus alot of sales made will be small, or discounted to get the sale.