Local school budget forums have been statutory in Wales since 2004.
Comprising heads, unions, governors, teachers and local education authority officials, they were intended to provide information for schools on funding issues and give them an opportunity to influence councils' budget planning and spending decisions.
However, many heads say they are mainly ineffective in explaining where cash has come from, with some of the local authority-led forums performing better than others.
The National Association of Head Teachers (NAHT) Cymru wants its members to become more organised and informed as part of a network able to take on the "powers that be". Information will be sent to all members soon, including details on their rights, a timetable of key budget-setting dates, and a list of questions to ask at forums.
Pat Clarke, past NAHT Cymru president, said she would not stop until there was more clarity in funding practices. As head of St Mary's church-aided school in Overton, Wrexham, she claims to spend half her time chasing cash.
She said: "I have got to the stage where I have to put on fundraising events so my pupils can have the basics, such as books, pens and papers.
"If officials are not going to clear the funding fog then we need to do it at the grassroots and find out where the money is going. If everyone is aware of basic information, budget deadlines and their rights, we can put up a fight."
John Evans, outgoing president of NAHT Cymru, said the forums needed to be attended by heads, teachers and governors to be a real force. He also claimed school representatives should chair more meetings in a bid to get more questions answered directly.
Anna Brychan, director of NAHT Cymru, said: "Our school budget forum network demonstrates school leaders' determination to make maximum use of existing structures regarding budgets and funding transparency.
"A number of our members are making a significant impact in local budget forums, and we are keen to communicate their expertise to members across Wales."
The budget forum network will meet throughout the year so members can share best practice.
NAHT Cymru is disappointed that a recommendation to overhaul the current school funding system, which is largely based on historical spending patterns, was rejected by Ms Davidson.