While browsing through Pinterest I found an article on how to make your own, and thought I would try it out. (I can't find the exact article anymore, but fyi the idea was not my own.)
I measured mine to fit my wrist comfortably, left a little extra room for the knot, and cut across the elastic at an angle. In order to make the knot, keep both ends of the elastic together, and create one knot. So easy!
As for my own, a (clean) empty candle holder houses all of my hairbands and headbands. (I have a slight candle obsession, so reusing candle holders is a must!)
Hope you get the chance to try this out, much cheaper than the Anthropologie or Twistband versions, and simple to make!