It could cost £155m to create a rail service between King’s Lynn and Hunstanton, according to a steering group.
Members of King’s Lynn to Hunstanton Railway Project met with council representatives in October.
A presentation by Peter Wakefield of pressure group Railfuture suggested the work on the 15.3-mile route would cost around £155m.
Mr Wakefield also admitted it is “extremely unlikely” funding would come from Norfolk County Council.
An update from the steering group on the King’s Lynn Hunstanton Railway Project Facebook page said: “It will be necessary to consider funding from the private sector to build the route in return for an arrangement to pay back costs over 60 years.”
It is a model being considered by Cambridgeshire and Peterborough Mayor James Palmer for the March to Wisbech rail link.
Mr Wakefield added that it would be possible to pay back the estimated costs if rail tickets were £5 per passenger.
The steering group believes both electric and steam trains could use the coastal line and say journey times between the towns could be 15 minutes, bringing more tourists to the coast and reducing traffic and emissions. A Change.org petition calling for the line has been signed by more than 2,100 people.