In its latest Convenience Tracking Programme, Him! quizzed 1,696 convenience shoppers immediately after they visited a c-store. Asked how much they would be prepared to pay for a product that cost £1 in a supermarket, shoppers said they would be happy to pay £1.14 higher than store staff had expected, with store managers estimating £1.12 and sales staff £1.10.
Only 20% thought price was "the most important element" of a c-store, while 48% of shoppers did not know the price of products before they bought them.
The findings will be seen by some as corroborating the Competition Commission's 2007 groceries inquiry verdict that supermarkets did not have an unfair price advantage over c-stores.
The Commission found that smaller wholesalers, which service c-stores, typically paid 13% to 16% more for goods than the big four and the Him! research suggests consumers are not unduly worried about those costs being passed on to them.
However, the ACS said Him!'s findings did not take pressure off c-store owners. "Customers accept that small-format stores can be more expensive, but for key products such as bread and milk there is still pressure on retailers to be competitive," said public affairs director Shane Brennan.
"There are other ways small store owners can compete rather than simply price-matching, including customer service."