We used to get a small DVC member discount, but that ended when the Childrens Place took over the stores. Now that ownership is going back to Disney, perhaps it will change.. or not.
My DS bought his first AP this year, and received the Mickey Monitor in the mail yesterday. There is a promo going on right now for AP holders - 15% off at the Disney Store, till June 30. He can also get 10% off online until June 15.
Are you talking about buying a DVC AP at the Disney Store? I don't think they sell them there. You get them by calling member services or go to a guest relations/ticket window at the parks or Downtown Disney.