I didn't know about the charm when I ordered mine but what a surprise!
My awesome SA gift wrapped my bags just so that I can have the charms! She thought I might like them and of course I LOVED them.
I got four more items for my mom and sister's Christmas gifts and have them gift wrapped and shipped to them. However, I took out the charms from their packaging.

Hehe... Now, they'll get beautifully wrapped boxes without the charms. Oh well.
I ended up hoarding SEVEN charms.
As far as I know, there was no minimum charge to get the charm.