I started my bracelet this past summer, and it is now completely full and ready to start another. I bought several of the Disney backstamped ones down at WDW earlier this month. They are sold in Italy, at WOD and in the watch store at MGM. You can also find them on eBay, sometimes cheaper than retail. There are also watch faces that have the bracelet part designed to add the charms to them. Makes for a really nice watch.
These have been very big on the West Coast and are just now getting popular on the East Coast. I undestand sales have tripled each year they have been available.