I'm unsure whether a third series has been or will be produced. Since these first two series were released several years ago, they probably aren't in vending machines anymore -- with the possible exception of mixed-content machines which are often used to get rid of older stock. Thus, I'd recommend searching eBay, Amazon, and other online retailers. These should definitely be available there.
This conversatin was a long time ago, but Im pretty sure I have the worlds biggest collection, with the exception of A&A Global Industries. There is a vending maching FULL of them at the Palermos I live by. I go there almost every day to get them, before they are gone