I usually shop at Waitrose,Sainsbury and Costco, with the odd trip to tesco and lidl, and we use our local butcher often. Waitrose certainly doesn't have as many things on offer as the other stores, but when I compare basic items that i often buy (organic milk, juice, butter flour etc) the normal price difference is minimal (less than 3p difference). Waitrose has lots of expensive items that are not available elsewhere which adds to the bill, but we do use those items. I was shocked to try ASDA one day and two items I was looking for were 5 p more than at Waitrose..... I think it depends on what you are buying, and the offers are certainly worth to other stores for. I live in London, by the way.