Ha Ha, any crafter would say they never have enough supplies. But for this lesson you actually need very little.
You need about 10 grams of wool for a bracelet. That is enough for a bracelet of 18cm - 22 cm in length and 4-6 cm in whit.
But it is nice to have some extra wool in different colours for adding extra effects to your bracelet.
If you are making wrist warmers, then I would double the amount to 20 Grams.