I get the canadian night crawlers from walmart for $1.50-$2.00.. Not bad, but you have to check and make sure you don't get a container full of dead ones
idk exactly what they use in the green crawlers, but my mom used to raise worms, and she got a bunch of those once just to see what would happen... After they were kept in normal soil with normal food for a couple of months they started to look normal.