I would check sites on the internet, including ebay, that sells trains at auction. Also visit a dealer of collectibles and antiques, and that may specialize in selling models. You may go to a dealer that sells model trains and accessories.
Go to the library, there are some very good reference books that could help. In the reference section there should be some books on the value of collectibles. Be a bit conservative in your estimate should you try to value them yourself. But, I do think that I would have a professional appraise them.
I'm not trying to evade giving you an answer, but their value may very by region. To get a good honest appraisal, I would have them appraise by a professional. It may not hurt to have several done. It would give you a better feel for the value. There are some that would "low-ball" you just to get the opportunity to get their hands on them.
The will be graded by the appraiser and then valued.
I describe value as the point at which two fools meet. One for selling so cheap and the other for paying so much.
What you have a re very good quality pieces. Take care of them. Good luck