The amount of money spent on special needs provision in Wales next year will vary by as much as pound;400 per pupil, according to new Assembly government figures.
Caerphilly will spend the most on additional learning needs (ALN) - almost pound;950 per pupil - compared with the Vale of Glamorgan, which will spend pound;535.
Increasing disparities in funding have led to calls for local education authorities to work in partnership to ensure that ALN pupils get a good deal wherever they live.
More than 1,000 children already have to be educated outside their home authority - in special schools or mainstream classes - because of provision gaps in Wales, according to critics.
Local authorities with good services, including Cardiff and Newport, will recoup thousands of pounds from taking in pupils farmed out from other authorities that have inadequate provision.
Ceredigion council, by contrast, has no special schools and will have to send about a dozen pupils with special educational needs to be educated beyond its border.
Gareth Roberts, Welsh president of the special needs organisation Nasen and deputy head of Llanrumney High School, believes regional partnerships that cross local authority boundaries are the only way to get a better deal for pupils.
"These (partnerships) could be very effective," he said. "They would benefit from economies of scale and would provide more consistency."
Critics believe the high number of local authorities in Wales has led to a lack of specialist provision and unnecessary duplication of resources.
Local authorities also differ in how they deliver their funding; ALN budgets include provision for children with special educational needs (SEN).
Ceredigion, for example, plans to delegate three-quarters of its SEN budget directly to schools next year, but it will still have to find provision for children with severe learning difficulties outside the county.
Anglesey, by contrast, will retain four-fifths of its ALN budget within the authority, rather than passing it on to schools.
Gwyn Parri, Anglesey's head of education, said schools have a duty to provide for pupils with a range of learning needs.
"An element of delegation of funding to secondary schools (in Anglesey) has already taken place through a local authority-driven pilot scheme: the monitoring of expenditure, at individual school level, has been most successful," he said.
Mr Roberts said councils had a difficult balancing act when deciding how much money to pass on to schools.
"Authorities provide additional services such as educational psychologists, which are there for the benefit of children," he said. "But if they delegate all their money to schools, these services could suffer."
Mr Roberts said the issue was further complicated because local authorities can set their own criteria to decide which children are eligible for statements of special needs.
The number of children with statements decreased slightly in 2008-09, in line with declining pupil numbers.
Mr Roberts said councils are currently only required to have "regard to" the official SEN code of practice, which includes taking into account the wishes of the child and parents.
"It has come out very strongly from parents, families and a range of professional bodies that people want SEN statements to stay," he said. "But they do want less bureaucracy, the timescale to be shortened, and a strong expectation that all authorities must comply with the code of practice."