If there is a Steinberg Resale Wizard there must be used Cubase licenses for sale, so how do I find out where the “for sale” is?
You search the web…
The Steinberg Resale Wizard shows you what the proper method is to sell (or purchase) used Steinberg licensed software. Steinberg does not sell previously owned software (only the latest versions) so, as svennilenni posted… you need to search the web for someone selling used or, if lucky, NOS software. Good luck. 
Regards 