We used to fish for them as kids. Put a piece of meat or even catch a small frog and step on it. Then drop it down close to the crawdad and once the crawdad has a hold of the bait, just lift it out of the water and drop into a pale or bucket. You can catch twenty to thirty of them in about 10 minutes. Sometimes even let the bait sit in a spot for a couple extra seconds and you'll get more than one. We never bought any live bait, especially crawdads.