Well, I called the expert, Steve Lopponow, at Venison America. "Babba" means "Baby". So NZ Babba Bones are NZ Baby veal bones.
He's actually selling 40Lb boxes of just knuckle babba bones, already cut up into 2-3" pieces for $1.45/lb. And it only costs me $5 to have them delivered to my house in St. Paul. He says "It's prime stuff!".
So, I see more demi-glace coming my way soon!