Supermarkets in the North are under siege from bargain-hunters from the Republic eager to stretch their euro in the run-up to Christmas.
Customers from the South have been arriving in Border towns such as Newry and Enniskillen in their thousands to benefit from significant savings on many goods including alcohol, toys and household items.
New figures show that visitor numbers from the Republic have almost doubled on last year, with most taking advantage of the bargain prices. Last year's figures were in addition to a 25 per cent increase on the previous year.
The invasion was spurred by a series of surveys showing that Northern Ireland branches of some chains were charging customers significantly less.
The European Consumer Centre in Dublin said yesterday that consumers should maximise their spending power, and it is clear that savings are being made by going North.
"We are hearing numerous tales of car-parks being full of cars with Southern plates in towns like Newry and Enniskillen," a spokeswoman said.
"In some cases stores which have outlets in the South and in the North are charging quite different prices for the same items.
"We would urge consumers to be wary of such differences in prices."
In Newry yesterday the Quays shopping centre car-park contained many cars from the Republic. Customers said that despite long queues and sometimes frantic exchanges with other shoppers and staff, going North was worth it in terms of savings.
At one stage customers from the Republic were queuing for over an hour and a half at the check-outs in the Sainsbury's off-licence.
Mr Seamus Gordon ,from Co Louth, who travelled up to Newry twice last weekend, said: "I've four young kids, and being able to save a few quid makes Christmas that little bit more bearable. I know it's manic when you're there, but it's a bit of fun anyway."
Ms Sarah Cummings, from Santry, Dublin, said the trip represented "good value for money and was certainly a prudent exercise".
Elsewhere, figures published by Belfast city management this month outline the surge in Southern shoppers to the city.
A spokeswoman for the Belfast city centre manager's office said: "It is clear that many people from the South are aware of the vast opportunities Belfast has to offer when it comes to shopping."
The highest sales were recorded in the off-licence section, with the biggest seller being a 24-pack of Miller Genuine Draft, retailing in Newry for £13, compared with € 43.20 in the Republic.
Shops such as Sainsbury's and Dunnes Stores in the Border towns have been quick to court the Southern trade by offering competitive rates of conversion from euro to sterling.
In some stores, customers have been offered 73p for every euro, well above the current rate of 69p.