the P.O. only allows books and bound magazines (although I cheat on that) for a media mail.
I just bought the $4+ boxes to send some fabrics to Board members - much smaller than I'd expected. I'm sending fabric to 5 women, so the next size up is too much - c.$10.

I sent out 3 large manila envelope 9x10? and it cost more on media mail than the 4.90 white cardboard envelope for the same size. So with crumbs...i think this is the better deal unless you use the 6x9 manila envelope, should run around 2.50 or so.