Researchers from Dumfries and Galloway Citizens Advice Service (DGCAS) found identical items cost £12.43 total in the town centre, compared to £16.60 in Dumfries North West.
And the further into Nithsdale you go, the more expensive it becomes with an average basket price in Moniaive, Penpont, Thornhill and Auldgirth of £20.12 for the same goods.
The Cost of Living: D&G Shop Check report compared the prices of 11 household basics, including bread and milk, around the region.
And they found that shoppers in some areas are paying up to 55 per cent more for the same items than people a few miles away.
And, in general, those in the poorest and the most rural areas are paying more than those in the better-off urban areas.
DGCAS chief executive Sue Irving said: “Local people will be shocked but possibly not surprised by what we have found in this study. It reveals that shops across Dumfries and Galloway are charging massive differences in prices for the same basic household goods, costing some families hundreds of pounds a year.”
During one week volunteers and staff visited 38 shops and supermarkets.
They found a trolley of identical items cost on average £17.70 – but could be as cheap as £9.95 in Tesco Annan and as expensive as £22.26 at the Co-Op in Upper Nithsdale – a mark-up of £12.31.
Sue said: “When we compared the prices we were amazed at the differences.
“We think this is difficult to justify particularly when so many local people are struggling to make ends meet.”
The report is part of an ongoing study by DGCAS into rural poverty in the region. The next part will focus on the costs of rural transport.