I would suggest you keep your eye on Ebay for good deals. Buy a 34" catchers mitt designed for softball (wider pocket). As others have mentioned, you are not trying to throw out base runners so extra padding is more important than quick transitions. Some catchers mitts are made exclusively for a woman's hand without much adjustment - velcro is your friend! If you can get this Mizuno glove for less than $60 it is a steal!!!
Mizuno MVP Prime Series GXS53 Adult Softball Catcher's Mitt New 34" 041969738344 | eBay
Mizuno MVP Prime Series GXS53 Adult Softball Catcher's Mitt New 34" 041969738344 | eBay