I would also like to point out, if I understand the update correctly, a
potential gotcha on paypal transaction fees. If listings default to
immediate payment required, customers who are purchasing items with free
shipping have no incentive to combine...
I'm not looking to rain on your parade, but I would caution you to look
at the impact of the flat rate % on your more expensive items. This may
may cause you to opt for a cheaper domestic bubbly rather than true
champagne. I hope it works out for you...