Mean Salaries. The Bureau of Labor Statistics reports that food preparers and servers at elementary and high school cafeterias earned a mean wage $23,690 a year or $11.39 an hour as of May 2013. Cooks at school cafeterias averaged $22,980 a year or $11.05 an hour. Both were higher than the average for other food preparation and service employees, who earned a mean $21,580 a year, but lower than the average for cafeteria and institution cooks, who earned a mean $24,670.