One of the factors that impacts on the amount of money available to pay teachers is the ration of students per teacher. A larger class size can reduce the salary burden on the school, but at the expense of reduced individual attention to the students. It also presupposes that the classrooms are spacious enough to accommodate additional students.
Of course, while some students need less attention and direction than others, determining what’s best for a particular student ahead of time is a tough challenge for both educators and parents alike.
In addition to class size, consolidating the number of educational institutions competing for funds in the same community can also help (economies of scale), but that opens up a Pandora’s box of issues like different hashkafos and backgrounds and the location and size of school buildings.
Other possibilities include reaching out to the surrounding community for dependable volunteer labor, perhaps for cooking and serving meals, grounds-keeping, tutoring, chaperoning school trips, office work, etc.) not all that different from the way many synagogues survive.