You can get them at DL. I have a bunch I got from ebay, too.
They all have things to do with me/my family...
Creative Memories ones, Disney's 50th, country flags I've been to, scrapbooking, movies and popcorn, RN & NICU, favorite flower, Starbucks Tazo Chai - stuff like that.
They used to be a HUGE thing, but not so much anymore. I still see a lot of people wearing them - the ones that got them because they liked them. The people that got them because they were the 'thing' to do don't wear them as much anymore.
I added a watch to mine so it's useful, too.
If you're going to get some for the girls, add a watch and get ones that have to do with their personal interests. And you don't need to get a lot - have some blanks in there so they can add to it as they go to different places.
eta: you can find them many places. They used to cost up to/over 20 for some. But you can now find them for MUCH less. I don't think I've paid more than 7 or 8 for any of mine - usually only a couple of dollars. The most expensive one I have I got at DL - it's a double sized 50th one.