People come to the American OO Today site for a variety of reasons, and one is to scope out values of vintage models in our obscure gauge and scale.
First, thank you for visiting! It is not like American OO is the most visible scale today. As an aside, I was told recently that the new TCA museum has not a bit of American OO on display! Please surf around the links a bit and get up to speed, models in American OO were in production and available from the early 1930s into the early 1960s and there were a lot of enthusiasts in the gauge, especially before WWII. It was manufactured in large commercial quantities by Lionel and Scale-Craft in particular.
My main article on Lionel OO is here.
So what if it is not Lionel? Right or wrong, an otherwise similar Scale-Craft item (die cast and similar quality level) is worth something like half of the Lionel equivalent. My main article on Scale-Craft OO is here.
Speaking generally most brands of American OO are probably worth half as much as Lionel OO, but there are major exceptions due to rarity and such. Some items are hardly ever seen for sale (such as the sand-cast Nason locomotives--more on Nason here) and when they show up on eBay there can be a bidding war. I know too, from the website stats that people will research up on things after they see unusual listings. So as a seller rest assured if it is an interesting item it will probably sell at a nice price, there are enough people looking for unusual OO items.
That said some stuff is relatively common, especially Scale-Craft. Most of their line was manufactured in large commercial quantities for a long while. The bad news being that common freight cars in so-so condition are probably worth $10 or less, especially with postage cost being part of the equation for buyers.
pre-war Hoffmann cars at left almost never show up for sale. People are curious about the unusual.
Trucks are another interesting topic. Speaking generally trucks could be around half of the value of the item they are associated with. But easily could be worth more, if the trucks are more desirable or in good shape. One big problem being that a sizable percentage of Scale-Craft bolsters have shrunk/distorted over time, leaving those trucks inoperable.
I quietly sell some things from time to time. I can understand the reasons to not price too low, I don’t want to give stuff away that I took the time to list. I list at what I think is a fair price though, and that is all any of us can really ask.
In short, American OO does have some value, don’t throw it out! Give eBay a shot if you are a seller but with reasonable expectations. Most OO will not command nearly the same pricing as seen for mint Lionel OO models, but most will sell for enough to be worth your time to list it and will be appreciated by the buyers.