With four cats to feed, I tend to particularly notice the price of cat food.
My lot like the 'Go Cat Crunchy & Tender' range and, originally, most big supermarkets were selling it at £3.10 or £3.20 for an 800g bag. Morrison's reduced it to £2 per bag but then put it back up again to £3.20. Sainsbury's also reduced it £2 but then put it up to £2.50. Tesco kept selling it at £3 but offered it on a '2 for £4' basis for a while, before removing the offer and then, a few weeks further on, reinstating again. Asda dropped their price from £3.10 to £2 and, thankfully, it seems to be staying there. While all of that was going on though, B&M have held their price at just £1.99.
I tend to buy 4 bags of cat food at a time, so (just based upon that one item alone), shopping in Morrison's would cost me nearly a fiver more than going to Asda or B&M.