Just my two cents, knowing a little about Scott Mann's business; remember that Sunset/3rd Rail/Golden Gate Depot is NOT a "high volume" provider of rolling stock. Thus, their "lower volume" lends itself to "hand made" precision brass steam locomotives and cabooses, for example. The ABS "plastic body" diesel models still have low volume brass under frames, and thus tend to be higher volume than the hand made steam models, but nowhere near the higher volumes that would be required to manufacture these modern freight cars being discussed. Therefor, the projected sell prices would be well above the $500 per set threshold, in my opinion.
Like HW, I know some about Scott's business and HW has described the Sunset/GGD market perfectly.
In the past, Sunset has offered some freight cars and cabooses, all in brass with one exception. I don't believe most of the 3 rail market is willing to pay for these cars at brass prices, and the 3 rail market would seemingly be where the vast majority of sales of these cars would be.
Jeff Sohn stated an excellent point recommending folks talk to Atlas about doing these cars. They do both 2 and 3 rail rolling stock and may be a better choice than even Lionel and MTH since Atlas will satisfy the 2 rail market. Joe Hayter at Weaver Models is another possible option for making these.
Fact regarding Sunset/3rd Rail and freight cars:
Scott announced the PRR X31 box car in plastic several years ago and received less than 100 reservations. Lionel made the car and sold thousands.
