I've had good luck with the small metal barretts that you bend and they pop open and close. I used them on both Gracie Ruth & Yogi when younger and growing out the topknots. I've found them at Drug Stores, Target, Walmart, Kmart and earring boutiques.
I've also had good luck with the tiny scrunchies that are available. They are as tight as the grooming bands but hold the hair nicely once it's long enough for a pony tail. DH had trouble in the beginning getting it wrapped around enough times to actually stay in. So he'd put the scrunchie in and then clip one of the metal barretts above it. It worked well and he eventually got to where he could do the scrunchies by themselves.
Another plus about both of these options is that there is very little hair breakage involved with them.