In the weight column, you could store the shipping amount for each item.
Then set the shipping rule to use:
Total number of unique items in the cart > 0
Based on column subtotal
subtotal of Column "Totalweight" "plus" "0"
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.