Paul Forrest, an expert at the West Midlands Economic Forum, said scrapping the controversial scheme would cost around £3 billion, a saving of £9bn on the cancellation bill predicted by ministers who are backing HS2.
He said costs could be brought down by reusing land – such as bringing Curzon Street station in Birmingham into the existing rail network – and selling off other sites.
"Their figures simply don't add up," he said. "All of the work that has been done by HS2 is design and groundwork. They haven't actually laid any track.
"As a result it is still possible at this late stage to redirect whatever groundwork has been done to facilitate local regional commuter traffic."
West Midlands Mayor Andy Street is among those to have warned Boris Johnson that cancelling the project would incur "a huge write-off".
The line, which has been described as the "biggest infrastructure decision since World War Two" by government officials, is expected to get the go ahead today after an official review reportedly backed the scheme in full.
However, concerns over its cost have persisted, with the review saying the final bill could be as much as £107bn – almost double its budget from 12 months ago.
The National Audit Office has warned of further cost rises, admitting that it was "impossible to estimate with certainty" the eventual bill.
The decision on the line, which is set to run through 45 miles of Staffordshire countryside, is also expected to expose rifts among Tory MPs, many of whom are desperate for it to be scrapped in favour of improvements to local services.
A new report, Connecting Britain by Rail, has unveiled a series of proposals based on the German rail system, which favours connecting city regions and developing local connectivity to 'hub-cities'.
It comes after the West Midlands Economic Forum outlined plans to use funding earmarked for HS2 to improve local services, including electrifying the line between Shrewsbury and Wolverhampton.
Mr Street insists that these improvements can take place alongside the construction of HS2. He recently launched a 20-year transport improvement plan featuring 21 new rail stations as well as 380 additional Metro stops and 150 miles of new tram lines.
The work is expected to cost £15bn.