I've sent out two already. Mailing CDs is cheaper than mailing books,
under $2. You don't mail the jewel case, but simply fold the wrapper
you print out around the CD and printed matter enclosed in cardboard
-- I cut it out of some old manila folders, which already have a fold
in them. The site rakes $.49 on orders you place, though.
I haven't yet explored Swap a DVD, but it
may end up playing a part in my New Year's de-cluttering, too.