I got mine here:
Custom Silicone Wristband Tool by Shanrene
I used the site's specialized design tool (a link is on the main page of the site) to make mine. I put our last name on the left of each, our two cell phone numbers on the right in two lines of smaller print, and a picture icon on each end. DD got butterflies, and DS got stars.
I spent somewhere around $15 for 6 bracelets plus shipping. I got three for each child, since I thought they were such a great idea in general. I got them a couple weeks ago, and I'm very happy with them! Also, the kids love them, so they'll be likely to wear them and keep up with them.