Loretta talked me into getting some FHM.
Did I say FHM? I'm pretty sure I just said minnows. I prefer Bluntnose or Spot-Fin Shinners for minnows, they seem to persist longer.
You could get a couple dozen minnows, let them multiply and establish first without predation and then add your sunfish or you can add as many lbs. as you want with your sunfish. A few pounds of minnows even in a small pond won't seem like many once they are released.