Was at work in Sainsbury's yesterday morning and a customer asked me if this really was £1.00 down from £12.26. I checked the price ticket, and was also shocked at the price.
The item will most likely not be in smaller stores, and may not be on the ordinary shelves with the other air freshners. (but could be). Also, I wouldn't recommend making a trip to Sainsbury's just for this product.
Note: The product also comes with batteries and is refillable. Refills are however a bit pricey at £3.37 at Sainsbury's and most probably similarly priced elsewhere. Also this is WHILE STOCKS LASTS- The store will not place an order for more stock other than the stock remainin in-store.