Neighbouring Cheshire East Council spent £40m on 624 independent school placements in 2023-24 - an average cost of £64,000 per student.
It has a SEND deficit of £78m - the biggest in England.
Former council leader Sam Corcoran said: "The system is broken and it is breaking families and councils.
"Funding has not kept pace with demand and the number of special school places is vastly outstripped by the number of families with children needing one."
Mr Corcoran, who quit in July just before he was due to face a vote of no confidence over the state of the local authority's finances, claimed mainstream schools were "starved of funds" and "do not have the resources to cope".
The Labour councillor said this meant "too often, children are having to travel long distances to out-of-area placements".