Lately I realized I rarely exceed the £2..20 (2nd) or £2.70 (1st) postage rates when selling multiple film cartridges. This is because most people don't buy over 1 or 2 carts at a time. So I decided to knock off the additional postage for all carts and either knock off or reduce the extra postage for all additional process paid cartridges. So now if you're buying S8 or 16mm film you can save a bit of money on the postage. I guess every little helps.