For multiple purchases at the same time the shipping cost remains a total of 66 cents (request an invoice from the seller before paying).

 After you have purchased all the first day covers you want and before you pay, please request an invoice from me thru e-Bay so you are only charged 66 cents per my agreement in the item description above. Once you pay without requesting an invoice there is not an easy way for me to credit you back for the additional postage you have paid.