I’m interested in whether you use mainly the unit price (price per unit of measure) or mainly the selling price (regular or special offer) to compare the value for money of grocery products in constant measure pre-packages, for example breakfast cereals and milk.
I almost always use the unit price, and the quantity information, when I want to compare the value of pre-packages of different brands, sizes and products.
And, usually I only do that when there is a special offer to be considered, or I notice (usually by a change in the unit price) that a regular price or the quantity in a pack has changed, or if I am buying something for the first time. Most of the time I already know the best buy for me and so am on automatic pilot.
What do you do and why?