There are many bargains available in Supermarkets. Many cheaper brands that in most cases retain enough quality to make the price good value. There are some things though where it is worth spending a bit extra for the good stuff. To my mind these are:
Free Range Eggs
Tea Bags -Yorkshire, Builders, Tetley, PG - own brand bags are a definite no no
Sliced meat for sandwiches
Washing up liquid
Are there any more?