I've run into a rather perplexing situation trying to add another item to my product line (it's tangible, not digital).
I'm currently selling a single product (let's call it ProductA) that allows purchases of 1-4 units at a time. I've set up an automatic discount for quantity purchase orders of 2-4 units. I charge flat rate shipping costs that are different for International, Canadian, and U.S. customers and that works fine.
My problem is in trying to create a shipping rule for my new product (ProductB) that I want to make available. My minimum purchase order size for ProductB is 2 units and the maximum is 3 units. The 2-unit order retails for $320 and the 3-unit version will cost the buyer $450. I don't want to sell ProductB as a single unit. Because of shipping costs, customers will have to buy either 2 or 3 units of ProductB at a time. If I create these as two separate products (2 units = Product C / 3 units = Product D), when it comes time to check out using the E-Junkie Shopping Cart, customers are given the option to buy ONE unit, and the shipping cost shown on that page is a lower figure that is associated with my other sales item (ProductA), not with the shipping rule I want to assign to ProductB.
If it helps in coming up with a solution, the cost to ship either 2 or 3 units of ProductB is exactly the same ($16.50).