Christina,
If the stein is marked “Made in Germany”, it just means that it was made before 1949 or after 1990. Most steins made after WWII have little interest to collectors and have little value. However, there are some exceptions, so each stein would have to be evaluated separately.
If by being in storage you mean the steins are in their original packaging, then they are most likely modern steins, but the packaging would not increase their value. As for selling in groups, it might help some. Instead of NOT selling three steins for $10 each, you might sell the three for $10. There would a savings on shipping to the buyer.
I suggest you do some research on your own. Look for steins like yours on ebay, or search the Beer Stein Library by the text on the stein and the number on the bottom. Check the Chapters page of this site to see if there is a collector near you that would be willing to help.
