Here at The Ceramic Shop, we carry a variety of mold soaps for your casting needs.  We have mold soap concentrate, which is a great way for production outfits to purchase mold soap; this gelatinous product will stay consolidated until you need to use it, at which point you just add water.  Pure Lube is another popular lubricant that we carry; this is available for purchase in various quantities for the studio artist or classroom.