I have small wrists too, and love mine. Very comfortable. I have the Castle charm and am planning to buy the Tink one (if I can find it).
According to their website, you can find them in the following stores:
Uptown Jewelry
Agrabah
Pirates Bazaar
Emporium
Once Upon a Time
Tower of Terror
Hilton Bonnet Creek
Ink and Paint
Mouse Gear
Calypso
Donalds Double Feature
Everything Pop
World of Disney
Trend
You can also buy them online at the
Disney Store. They did release a bunch of new ones recently.