Hello!
There is a store but I don't know if it's conitec/ oP group only: http://www.shareit.com/product.html?cart=1&productid=300164483&languageid=1
Some tools and textures are sold/ linked on the download page: http://www.3dgamestudio.com/download.php
Normally all other stuff gets advertised and sold here: http://www.opserver.de/ubb7/ubbthreads.php?ubb=postlist&Board=3&page=1

Try: support@3dgamestudio.net