Both options are capable of raising about $300 million a year to fully deliver a $30 billion roading and public transport building programme over the next 30 years.
Traditional funding sources, including fuel taxes, road user charges and rates, only stretch to $18 billion.
What's your view of the toll plan? Email us
It is unclear how the tolling of existing motorways would work, but it could be based on the Northern Gateway toll with sophisticated cameras and sensors to capture images of vehicle number plates.
The Northern Gateway between the turn-off to Orewa and Johnstone's Hill tunnels has a toll of $2.20 for cars, motorcycles and light commercial vehicles, and $4.40 for heavy vehicles of more than 3.5 tonnes.
One source said the toll would not apply to motorists driving through Auckland without stopping. A daily cap may apply.
Automobile Association spokesman Barney Irvine understood the panel of independent advisers to Mr Brown had left open possibilities of either charging drivers as they entered or as they left motorways through the city.
Mr Irvine would not comment on a likely toll of $2 for each time drivers get on or off motorways running through the Super City.
But he hoped collection costs could be kept as low as possible to reduce the impost on drivers, who have indicated in an AA poll they would far prefer motorway tolls to rates rises - if they have to dig deeper in the first place to fill Auckland's gaping transport funding deficit.
The association expects toll collection costs would be minimised by feeding extra income from Auckland motorists into the Transport Agency's existing Northern Gateway scheme.
Transport Agency figures show that almost 34c for every dollar collected from the northern toll road goes on administration costs.
New Zealand Council for Infrastructure Development (NZCID) chief executive Stephen Selwood said he believed Aucklanders were ready for tolls.
A survey of 1016 Aucklanders by NZCID in 2012 showed people were fed up with congestion and willing to pay to improve the situation, provided the solutions worked, he said.
The NZCID has argued for motorway charges of $3 at peak hours, $2 shoulder and $1 off-peak.
Auckland Chamber of Commerce chief executive Michael Barnett said Aucklanders had a choice of additional rates and fuel taxes or motorway user charges to meet the shortfall - "it's as simple as that".
He favoured a simple, predictable motorway network charge, saying that expecting 520,000 ratepayers to carry the bulk of the $300 million a year shortfall was unfair.
One project outside the alternative funding package is the $2.4 billion City Rail Link.
A mayoral spokeswoman said the rail link was included in a new 10-year budget, with the council's 50 per share funded from a mix of debt and development contributions. The Government is funding the other 50 per cent.
Last night, a spokeswoman for Transport Minister Simon Bridges said the Government did not want to pre-empt today's announcement.
Previous transport ministers Steven Joyce and Gerry Brownlee have said there would not be regional fuels taxes or tolling of existing state highways in Auckland.
