That does sound like a lot. Maybe you should ask for an itemized breakdown.

That sounds extremely high...I would have to find a different contractor to do this job or atleast give an estimate.

Unless we see the plans for the pre-fab house, I do not think we can legitimately call it into question. It might sound high, but it might very well be justified in the end. There are probably continuity tests that the electrician needs to run on a pre-fab like that (to make sure the wires are all safely connected). An electrician would not need to run such tests if he installed the wire, himself, on bare studs. Those same wires on a pre-fab can come loose (or get cut) during transport and cannot be visibly inspected because they are irretrievably inside the walls. It all might add up to savings in the end, though, because you still save the cost of all the framers, insulators, and drywallers putting their time in to finish the walls. As such, it would be a necessary, larger expenditure on one item in order to save far more on the other items in the construction project. You might also end up with a better, sounder product that was designed, engineered, and manufactured as one solid piece instead of a mass of unassembled parts put together under the risk of human error. It is not necessarily a rip-off.