Outfit prices are based on rarity of the outfit or its individual items, The condition of the items, original item boxes and their condition, paraphernalia that Lionel included with the outfit, and the desirability of the items or outfit.
Some items are more desirable than others to buyers. Conversely, there are even some older or rare items that are of little to no interest to buyers.
The value is what ever the buyer is willing to pay.
You describe the outfit as near mint which should sell for a few hundred dollars or higher. While you don't mention all of the contents, a dull black rubber stamped 258 2-4-2 loco from 1941 has a Greenberg's Pocket Price Guide value of about $100. It was cheaply made to save Lionel money, and not as popular with collector's as the Gunmetal version.
The 1679, 1680 1682 freight cars of that period are very common, not rare and therefore of little interest to collectors unless in excellent condition.
If you buy the set, please post a picture of the set and outfit box, and the individual items. We would love to see them.