I posted this a few months ago. Posting again as it's back at half price.
Rucksack half price at Tesco in store (in Newtownbreda store, Belfast - presume nationwide). I previously bought the "Tesco 70 + 15L Rucksack" for £34.25 and considered this great value. I've been very impressed with the quality. At half that price it's a real bargain. Still listed as full price (£34.25) on tesco.com.
They have a very similar 65L Rucksack for £12.50 on tesco.com.