I read about a new site today
MySupermaket.co.uk][url]MySupermaket.co.uk[/url]
It lets you compare prices from Waitrose, Sainsbury's, Tesco and Asda. I selected some of my usual purchases and to my pleasant surprise Waitrose was not really much more expensive, in fact Sainsbury's was higher! A sample of products totaled up like this.
Sainsbury's £37.68
Waitrose £36.73
Asda £35.40
Tesco £33.93
Very happy about that because I love Waitrose and never cared if we were spending more because their products are great AND the people that work there are friendly and helpful. (You can actually find workers on the floor that will assist you if you can't find something). Also it seems the customers are a bit more civil (its not a free for all with folks crashing into you).
PS - They are always fully stocked too!
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Always a pleasant experience!