House prices slipped back by 0.4% in September, according to figures from Nationwide, although many industry experts agree that the housing market remains relatively stable.
The fall in house prices increased the annual rate of decline to 0.9% in the region, meaning the average price of a house last month in the greater South West was £186,366 compared with the average national price at £163,964, the figures from the building society revealed.
North Devon saw the largest dip in prices by 8% in September and 5% since last year to £186,294.
In Cornwall and the Isles of Scilly, prices had increased by 1% since last year to £198,601 – but fell by 5% last month.
Gordon Millar, of Stags estate agents in Launceston, claimed there was not a "shadow of doubt" prices had fallen by more than 0.9% since last year in some parts of Devon and Cornwall. He estimated prices had fallen by 5% to 10% in East Cornwall, North Cornwall and North West Devon.
Mr Millar, who has been an estate agent for 45 years, said it was of "great concern" that prices in the Westcountry had escalated beyond many other parts of the UK.
"We face a stalemate unless prices fall by another 10% to 15%. Our main buyers from London and the home counties are going elsewhere, and they won't come back until prices are more reasonable. It is the worst slump I have seen in my professional career, which is a fascinating challenge for a property seller. We've got to find new ways to motivate people to buy."
Richard Copus, Westcountry regional executive for the National Association of Estate Agents and who runs Richard Copus Estates, said the housing market was stable and there was "nothing to worry about".
He said: "A 0.4% drop reflects people being more sensible about asking prices, and it balances out a 0.4% rise earlier this year.
"We should think ourselves lucky when compared to the situation in the Mediterranean and notably the property slump in Spain."
In England, average house prices fell slightly during the third quarter, and were down 0.3% compared with the same period in 2011.
Nationwide's chief economist, Robert Gardner, said: "We expect the UK economy to see a gradual recovery over the next 12 months, with house prices remaining relatively flat or declining only modestly over the same period."
The quarterly report on regional markets showed
London, the outer South East and parts of the North were the only regions not to experience a drop in their prices.