Questions to the Transport Minister, Keith Brown, show five land deals where property was purchased to build the line then sold off after the project was scrapped incurred a loss of almost £1.6m.
The Evening Times reported last month how land at Clark Street in Paisley was sold for £50,000 after being purchased for £840,000.
The land was bought from Airlink Securities Ltd, a parking firm. The company was then liquidated but its former owner, Mr John McGlynn, bought back the land.
Three other deals also led to significant losses.
A plot bought from Rentokill for £880,000 was sold to AKV Vehicle Rentals for £80,000.
Another plot, bought from JM Taylor Holdings for £240,000, was sold back for almost half the price, £124,5000.
Three plots were bought from Kenyart Ltd and sold back to the firm for £99,600.
Only one deal resulted in a selling price higher than the original purchase.
Four plots were bought from BRB (residuary) Limited for £5340 and sold to MTS Properties for £5400, bringing in a profit of just £60.
James Kelly, Labour MSP for Rutherglen, asked the Transport Minister a series of questions, including how much the Scottish Government spent on the GARL project.
Mr Brown said: "It was stated the forecast spend for the cancelled branch line element of the project would be £33.13m.
"As of 19 September 2013, £29.91m has been expended, giving a cost of £3m less than previously forecast."
Mr Kelly also asked how much had been spent on compensation and on individual land deals.
Mr Brown responded: "As at 23 September 2013 a total of £8.532m has been paid out of the public purse to settle all claims for land compensation."
He also gave the details of the individual property deals.
Mr Kelly, Labour's infrastructure spokesman, said: "This is an astonishing waste of our money and exposes the financial lunacy of cancelling a rail link which was supported by the business community."
A spokesman for Transport Scotland said: "These costs have previously been reported to the Scottish Parliament
"Around £176m of capital expenditure was saved as a result of the Scottish Government's decision not to proceed with the branch line element of GARL.
"Since the cancellation of GARL, routes along the Paisley line have benefited from £230m investment in rail infrastructure improvements alongside a new £430m fleet of Class 380 trains now operating in Ayrshire and Inverclyde."