A lot of last years bats are going for around $150 in online stores . SBFs does have some decent bats for that price. Usually can call them and get a little better deal. As for size, it all depends on the kid. My kiddo was swinging 32/22, 12U. I suggestion before you buy her a bat, have her try teammates or friends bats during batting practice. I seen too many parents buy the wrong size bats.
Honestly want to put her in a great bat for decent price, talk her into used. Buy one of the used Killer B Eastons from the Fast Pitch section. I put my kid in an used SSR3B last year, she wont go back. Her HRs arent clearing the fence, they are landing on the track.