Bethany,
Big enough to do this to a homer, or uppity nigra! However, be careful you dont want your purse to look like it is full of rocks. I usually go down by my creek to fetch the smoothest stone. No need to have bulges.
However, I do not have to carry that many stones now that I have my equalizer!!!
You can get a good stoning purse anywhere. I should have made mine but it caught my eye.