Just to add a little bit to what Don has said, those "little things" that are left to be done CAN be quite time consuming to do right rather than just slapping the parts in.

Don jsut got through laying a lot of the wiring in his project and I suspest he's got a good deal mor than just a couple of hours in it. THings like mounting the motor and transmission setting pinion angle etc is also something that is not to be rushed through.

If your having the work done at a top of the line shop with experience doing these kind of cars then they really are your best source for an estimate.