I get in 25 pounds at a time, local resale. For 1/4 pound a sandwich size Tupperware or other covered container works well, as you do have to store them in the refrigerator. A shoebox size container is good for a pound, you don't want more than 1/4" depth of worms in the bottom of the container.
Once daily fill with cold tap water, wait about 30 seconds for them to settle, and pour off the excess water. You want to store them with as little water as possible, too much water is the biggest mistake people make. They need air just as much as water. I net them out of bins & hang them to drain for a minute before bagging, this is for local pickup as well as regional shipping.
Folks breeding angels, discus, as well as smaller cichlids are big customers, as well as cory breeders. The only fish you have to watch out with feeding blackworms are strict vegetarians, mainly some plec & African cichlid species.
Rinse every day, store with as little water as possible, and refrigerate & they will keep for several weeks.
