I used to purchase GeoTrax for resale, but not so much anymore. GeoTrax are still quite popular, so you should be able find a buyer elsewhere. Consider joining our GeoTrax Community Facebook group where you can buy and sell GeoTrax. Facebook Marketplace, Ebay (Local), and Craigslist are other options.
If you need more specific advice on how to best get rid of your GeoTrax sets or have other questions or comments, send me a note.