Price is per (mounded) scoop.

Worm castings are...well...worm poop. Worm castings gently add nutrients to your plants' potting mix.  You can either top dress plants with worm castings or use them in your potting mix.  A suggested general purpose potting mix recipe is 60% coco coir, 20% perlite or pumice, and 20% worm castings.

Third photo shows typical amount of a mounded scoop.