Crazy thought, but before you go through a dealer, you may want to hit a show nearby and take your chances there. If you price things right, they will move, and you will do better than what is essentially wholesale (or worse...). At least you aren't shipping things - just put price stickers on them and see what sells. Maybe just take the more valuable items.
I really hate shipping trains that I sell - it's the worst part of the transaction. Everyone here on this site has been so easy/good to deal with that I almost feel obligated to offer things here first. But the shipping.... it's just such a hassle, especially for larger items like 5/6 car sets. Good like finding a box to fit the box...
But it can't hurt to at least advertise locally and see what you get. You can also post here "local pickup only" - that will minimize your market, but it's free at least. You might be surprised - if the deal is good and/or the item is rare, people will come to you.
Just a thought!