At this point, Postwar Lionel often goes for less than $100. Older Williams locomotives that are very robust often go for less than $100 as well. Some of the basic K-Line locomotives are also good values such as the semi-scale Alcos based on the Kusan tooling. Anything that is conventional and not true O scale will often be priced very well these days unless it is a rare item or in the case of Postwar, in the most pristine condition.
I haven't gotten around to it yet, but I have multiple locomotives I plan on selling for less than $100 each. Not offering them for sale directly here, but once I get around to it, they will be on the buy-sell forum.
