for the most part, most of them are generally available second hand on ebay or other website. the metallic livery ertl are extremly rare.
My Trackmaster/Tomy/Plarail Photo Gallery Page (over 600+ photos and still under construction)
https://www.flickr.com/photos/183311600@N03/
https://www.flickr.com/photos/183311600@N03/