The computer estimating program I use works the same way in either getting a base bid or a change order. It basically has a price based on the average time to install an outlet with an average length of a conduit and wire run. Like all averages some runs are longer and some are shorter, but all assemblies will have the same components (e.g. a box, wiring device, mud ring, and cover plate).
It sounds to me like you got what you asked for.
Extras and change orders on jobs that are caused by owners or designers who change thier minds after a contract is awarded need to ask themselves why they did not make that change before bid day. They are always percieved as expensive.
Good luck.
