You can make an incredibly potent dye with just a small handful of stones. I often make dye pots with the skins and stones from 5-7 avocados, which I can save up in just a couple of weeks. You really don't need a huge number. One tip is to ask your friends and family if they can save them for you too! One of the videos will tell you the best way to wash and store the skins and stones, and you can explain this to your friends.