Just went to Tesco to buy some caster sugar, a kilo bag was £1.09, I didn't really want that much so went to pick up a 500g bag, this was £1.19, so that's a no brainer. The larger bag wasn't on offer, it seemed to be the usual price.
Oh, I didn't mean I'd waste it, it's just the pricing structure, it encourages people to buy more than they need. It's probably a mistake but it was glaringly obvious.