Business Reply Mail
Only pay for the postcards that get returned. What a concept. For all of the postcards mailed within the U.S.A. I am applying for a Business Reply Mail First Class Permit. Since I have shipped out roughly 2,000 postcards and only received 80 I think this is the way to go. So much more cost effective.
Return2.Me 
that is a super swell idea, with our Sock Monkeys shipping outside of Canada drives the prices up a lot, it is a total pain sometimes trying to price them out, but they have gone all over the world now so i shouldn’t complain, was mostly empathizing as we made them for free for quite a while.