Let's see ... $19 for 3oz. Three ounces is ~90grams. Taking a direct approach of assumption, 3g per 'cup' of tea. Assume three steeps out of it, so 18oz of tea, about what most people get in a bottle of soda. Three grams makes thirty sessions with this tea. So ... $19 (shipping costs aside ... I know, I know) comes to $0.63 per cup. Compared to $1.25 in a vending machine for the soda, or $1.19 (iirc, the last time I bought one) individually at a store.
I'm not trying to convince anyone that it's wrong to not want to pay that much. It's just sometimes we don't realize just how little tea can cost, even for some more expensive ones.