The Competition Authority is urging schools to allow a number of different retailers to sell school uniforms. The authority said some schools still have a policy of appointing one exclusive retailer to sell uniforms.
It pointed out that competition between retailers tends to result in lower prices and better quality.
In May, the authority received a complaint from a retailer who wished to sell a school uniform for a school which had previously had one exclusive retailer.
However, the manufacturer refused to supply the uniform to them.
The authority intervened and the manufacturer agreed to supply the complainant with the school uniform in question.
The authority says "It is clear from our investigation that some schools still have a policy of appointing one exclusive retailer to sell uniforms. Competition between retailers tends to result in lower prices and better quality."
"We would encourage schools, where possible, to allow a number of different retailers to supply their uniform. Or if a school chooses to appoint a single retailer, we recommend they choose that retailer through a competitive tender, and not on the basis of established or historic relationships."
"Ensuring the best value possible for hard-pressed parents and families is important, particularly at this expensive time of year," it adds.