Consultants reviewing transport options have concluded that the preferred option of running trams jointly on newly-built light rail lines and existing heavy rail infrastructure would be the second most expensive option at an estimated £92.4m.
It compares to an estimated £207.4m to reinstate a heavy rail project, while a third option of running futuristic bubble cars, which could each carry four passengers and sets of luggage, was estimated at £71.7m.
The final report on the issue was jointly commissioned by Glasgow Airport, Transport Scotland, and Glasgow and Renfrewshire councils to find the best way to improve access to the airport, which can currently only be reached by road.
Last month, Transport Minister Keith Brown announced that tram-trains were the preferred option and a feasibility study was under way.
However, consultants Aecom noted that a "potential lack of capacity" on the existing rail network could hamper the airport tram services at peak times, and suggested shuttle buses may need to be used to carry passengers from Paisley Gilmour Street to the airport.