I think that some folks may be over estimating the condition of these trains.
There are tape marks or scuffs on the side of the tender.
Dust and/or dirt is visible on the engine and all of the rolling stock. The dirt may or may not come off with a light cleaning. (be aware that Lionel's silver paint is particularly hard to clean without damaging the appearance).
I don't mean to imply that it isn't a nice set. It is.
I purchased a very similar set in December 2012 via private sale. It was a 1505WS set, with a 3482 Milk car and a pair of remote control switches, all boxed, but no set box.
I'd guess the book value on the 3482 milk car is less than that of the 3662 milk car. But IMHO, it is actually more difficult to find. I paid $180.