Thanks to Carrie Stephens for taking things up a notch by suggesting an action! Here is the fully automated version...
1. Create an action with two steps a.) define brush preset b.) close the file - here is my version Download Make_brush
2. Put all your png files in one directory
3. go to File>Automate>Batch
4. Select your new action and the source folder. You don't need a destination folder. Click Ok and watch it go!
5. Go into preset manager and save your set.
By the way you can check out Carries site Fish Scraps here.