The insert in the newspapers includes coupons for Coors, Pot Noodle, Whiskas, Galaxy and Branston products and will reach a combined total of almost five million readers.
Vouchers for Buxton mineral water, KitKat, Gold Blend, McCoy's crisps, Ribena and Birds Eye fishfingers bring the total saving for customers to £3.10.
National newspapers are expected to take up the cause of the independent retailer with editorial articles over the course of the week.
National Cuppa Day, a new initiative from NIW organiser My Shop Is Your Shop, will see hundreds of retailers offering their customers a cup of tea on June 3. The event is intended to show the unique link between convenience retailers and the communities they serve.
MSYS chairman Alan Toft said the campaign had received more than 2,000 requests for its T-shirt and pos promotional materials, and that support from suppliers and wholesalers had reached its highest level since the event began in 2004.