Never, never give away your work!! Treat your builders with respect and they will reward you with recommendations to their clients. You are supplying a valuable service that homeowners want. Do not, under any circumstance, devalue that work by giving it away. As suggested by OEX, many companies have taken this route to their grave. Every time someone in our industry does this, the rest of us are devalued. Do you think an electrician would give away his prewire?