Waitrose has attracted ridicule on social media for selling empty jam jars for £2 - 29p more than the cost of one full up with jam.
Waitrose shopper John Kilbride, from Glasgow, noticed that a store was simultaneously selling the luxury Bonne Maman conserve for £1.71 and an empty jar for £2.
Some consumers defended the grocer, pointing out that the Bonne Maman was on temporary offer and the empty jar was bigger, despite their near-identical appearance complete with red gingham-patterned lids.
Others, however, suggested that the supermarket was clearly targeting "middle-class jam makers" and joking that it was clearly the "preserve of the wealthy".
A Waitrose spokeswoman said: "Our Bonne Maman conserves are on a temporary promotion and are great value for money."
The WI advises that sterilising jars for home-made jam simply requires washing them in very hot, soapy water, rinsing well and placing them on a baking tray in the oven to dry completely.