I'm sensitive to this issue as one who is halfway through building a second home! I hired a contractor to build/dry in the shell and am doing some of the remaining work myself and using local subs for the rest. I did the electrical rough in (except for meter-to-panel feeds) and the supply plumbing. I intended to do the DWV plumbing, but a local sub I paid to review my design/layout gave me such a good price, I had him do the work. I figure the elec/plumb work I did saved maybe as much as $25, but then it took me a long time working only on weekends while I have interest-only construction financing!
Local subs have also given us pricing that is not much more than it would cost me to do it myself for insulation (combo of sprayed cellulose and fiberglass), sheetrock hanging, sheetrock finishing, and wet area/tiling.
Recesed lighting fixtures are very cost-effective, as are the surface mount fixtures from the big-box stores. As others have said, WINDOWS (and exterior doors) can be a big-ticket item, but you really don't want to scrimp on them. We also spent a lot on good-quality and high efficiency HVAC. Roofing can be a big variable - she really wanted all metal roof but we compromised with composite roof over the main structure and tin just over the porches. I wish I had known beforehand that the nifty curved stairs in the "Grand Entry" would be such a HUGE cost; try to avoid such fancy "architectural" features if possible. We've scrounged hard for deals on hardwood flooring, mouldings, T&G ceiling boards, plumbing fixtures, etc., and I figure we've spend about 50% of typical for each of these. Still have to find deals on cabinets!
- Jay