I'd suggest a mid price ball, probably a pearl, and definitely one with a symmetrical core that would be more forgiving as she learns to release more consistently. Here are a few that I know about:
Brunswick - Edge pearl, Fanatic pearl
DV8 - Diva Style, Freakshow pearl
Radical - Jackpot pearl, Cyclops
Good luck to you. Feel free to message me if I can help further with layout ideas, etc.