I can't help with that exactly, but it is quite straight forward to make your own from cotton covered millinery wire. You can make them any size at all then, and either ribbon wrap them or paint them to any colour (I use acrylic paint!)
I use the extra firm millinery wire, which I think is 16 gauge? I also use the thin metal headbands a lot of the time because they can be shaped and adjusted to be comfortable. Wrapping them in ribbon helps them to have a bit more grip, but more often than not whether I use elastic or a headband I also have a comb too, to stop it from slipping.