This is true. Hang on to at least one bottle, even when it is empty, and try to find one that has comparable ingredients.maybe take a look at the ingredient listing and find a product that has something similar. Or the other option is to find a store that carries their product and still has old inventory lying around. Then just stock up!
You'd be surprised where you might find old inventory, too. Grocery stores sometimes have it, b/c a lot of people don't shop for their hair care at the grocery store.