There not in a multipack, i have only seen them as indervidual packs on the plastic hanging strips they have scattered around the supermarket. They move all the time, its a case of hunt down every aisle! There not always on the crisp aisle...... have found them with the alcohol, the cereal the tins!! have a hunt. I get them in my Tesco
There WELL worth it, by far the best. ( they do work out expensive though at 49p a bag - making it nearly £3 for 6! - compared to the multipack of 6)