Gay Mitchell, a Dublin member of the European parliament who belongs to the main Irish opposition party, Fine Gael, offered the advice after publication of two surveys that, he claimed, "show the rip-off Republic is still flourishing".
The first, by Eurostat, found Ireland to be one of the most expensive countries in Europe, with prices across a range of goods up to 28% higher than elsewhere.
According to the second survey, conducted by Fine Gael, supermarkets in the Republic are charging mark-ups of more than 200% on some of the food they buy from farmers. On a typical basket of goods, Superquinn showed the highest overall margin at 174%. Tesco was next at 157%, and Dunnes Stores was third at 154%.
Retail Ireland, representing the multiples, dismissed the findings as "groundless and grossly misleading". Director Torlach Denihan said the survey took no account of the costs borne by the retailer after the product left the farmgate, including processing, storage, refrigeration, packaging, advertising, marketing and distribution. However, Denis Naughten, Fine Gael spokesman on agriculture and food, maintained that, for most of the items surveyed, there was little or no processing involved.
He cited a 272% mark-up on a head of cabbage at Dunnes, a 245% margin on lettuce at Superquinn and 231% profit on a head of cauliflower at Tesco.
"Retailers are continuing to make huge profits from the Irish market at the expense of both consumers and farmers," he said.
Mitchell added: "Irish prices are now so high, you could take a cheap flight to Italy, buy your week's groceries and still save money."
The 80,000-strong Irish Farmers' Association called for legislation to force supermarkets to publish their profit margins.