Here is the website I have been using for priority international mailings:
http://www.usps.com/international/pr...ernational.htm
The "prices" link there says that both enveope and small flat rate box cost $12.95.
When I look at the "supplies" link and view all, I see only cardboard mailing envelopes. It seems to me that some of the people here are talking about softer padded envelopes or bags, as I can't see being able to stuff more fabric into a cardboard envelope than into a small flat rate box. However, I haven't actually tried those two options.
Is the mailing envelope we are talking about that cardboard envelope? Maybe my calculations were wrong on what the small flat rate box will hold, since it seems only half of what the envelope will hold.