I have a question re the return envelope for those who have done more than one set in prior swaps. I figured the cheapest way to send and get back two sets would be by priority mail flat rate envelope, but the post office said I can't prepare a return envelope label that will be mailed more than 4 days after I create it, so what do you do? Can you get a priority label at the actual post office (I print my labels online)that can be mailed at a later date? When I did the batik swap, I only did one set and it was cheaper to just send it first class mail, but this one, with two sets, of course weighs more and would be cheaper priority flat rate.