Kevin,
You are probally correct in saying that the real cost is the painting of the unit.
I watched a special a few months ago on how Lionel painted their engines and it was very time consuming, to say the least.
One thing that really bugs me, WBB has not changed their style of caboose! They still use the N5C for all caboose runs, not all railroads ever used an N5C caboose.
Reading Lines used an N6b caboose and other designs. Philly & Reading used woodside cabooses.
Williams has good quality but some of their engines and cabooses are fantasy designs!
Some railroads never bought a GP-38, but Williams made one in their railroad name and colors; case in point, Reading Lines used GP-39-2's, never owned a single GP-38 but Williams produced the model for Reading Lines.
In my opion to be successful in model trains; you must look at what was bought and used by a railroad and then model that, not what you want to model as it may never sell.
Lee Fritz