The information in the auction link is incorrect (about it being a pre-WWI stein).
Truppenlager Groß Born was not built until 1919. The uniforms being worn by the German troops on the stein are WWII era uniforms, so the stein probably comes from the period just before or during WWII. You can Google search about the military base – it was a HUGE training base up in Pommerania (with a capacity of up to THREE Divisions). Probably its greatest claim to fame is that it was the training base for the Afrika Corps.
I have no idea how much your stein would be worth, but you should take into consideration the size of the military base (and the large number of troops who moved through it) as well as the fact that the stein was not personalized. If it were my stein, I would consider trying to sell it as a piece or WWII militaria, which attracts a different group than stein collectors. You might see if you can leverage the Afrika Corps history – anything dealing with the Afrika Corps is hot.