I've been wanting to organize the girls hair stuff for ages, but I finally found the right container. The ponytail holders are on the top level, barrettes on the second, and the base is saved for bulky items like hair bands and claw clips. The container is a basic two tray tackle box from Walmart, I believe the brand is FlamBeau, but it's a classic design that would be easy to find anywhere. I paid less than $8 for this one. Seeing everything all organized actually makes me want to go out and get more now.
Funny Libby calls the ponytail holders in the top "berries" and carries them around like a toy once they fall out of her hair. She's quite attached to them.