I had the privilege of representing a client in a new home purchase earlier this month. The home is located in a very new subdivision in Richmond, TX. My clients found a great lot and a floor plan that worked well. I accompanied the couple to the builder's design center to help them pick out decor for their new home. We were able to find the basics: carpet, tile, granite, sinks, etc. As we were finishing, the wife asked about hardware for the kitchen cabinets. Oh yes, the builder would be glad to do that-for $15.00 per knob! What? They would basically take a $2.00 knob and charge $13.00 to install.
The buyers were shocked at this, but I tried to explain to them that this is really something the builder does NOT want to do. It's time consuming, and if not done correctly, could cause the builder to have to replace the cabinet door. Builders arrive at their pricing for a reason.
There are things you should have the builder do when building from the ground up. Go ahead and add that bathroom. Increase the size of the patio by having the builder pour more concrete. Put the bay window in. Choose the 3 car garage, or add a bit of additional storage space by converting a vacant space into a closet. Don't however, go overboard and spend an inordinate amount of money for the builder to do a basic handyman project. Some things are better left until after closing.