It is wise to find an appraiser, to get an idea of how much to insure it for. With something like toy trains like this, it is going to be a bit more tricky than any other collectible, because celebrity ownership may or may not change the value above other similar items. If I remember correctly, Tom's collection featured a lot of prewar (could be I am recollecting that wrong), and in the world of pre war trains, would collectors care if it was owned by someone like Tom Snyder, or would it only be worth what a similar item is worth in general? Personally, I suspect that it being Tom Snyders would not increase the value of it that much, people looking for celebrity collectibles probably wouldn't be that interested in something like trains (they generally like things like clothing, signed documents and so forth) and train collectors probably aren't going to be that hyped up on the celebrity aspect, they would be, for example, a lot more interested if Tom had a 700e because it was one, not because he owned it. Also add to the fact that Tom Snyder was not as big a celebrity as let's say a movie star or music star, he kind of was more of a cult celebrity (and I say that with all do love and affection, I liked his show a lot), so that would factor in, too. My guess would be it would probably be worth the sum of the parts, as if this was a private collector and not Tom Snyder, but I could be wrong, too, and I am not an appraiser, so you are smart finding out. I can say that at the very least, it would be worth what similar items go for, it is like old coins, especially gold coins, they are never worth less than the value of the metal in them
One suggestion I have, there are several big auction houses in NYC, Sotheby's , Christies and Bonhams come to mind, give them a call and ask them if they can suggest an appraiser to work with you, explain what you have, and see. Or maybe call one of the auction houses that routinely deals with appraisals, or maybe call the TCA train museum and see how they appraise their collection for insurance reasons,might have an idea who to get to do it.