I'm trying to get a group of 12 together for a case buy, but if I can only get a subset, say 6 people, what would shipping look like? I assume that if a case is 2-3x a single copy shipping, that 6 copies will be somewhere in between? Ie, We'll still be saving a bunch on shipping. Is there any chance that 6 could cost more to ship than a case of 12? (Shipping can be weird)