She has now spent $190 through OfficeMax for her two daughters who attend Sherwood Primary, but believes she could have done better herself.
"It's just a shocking expense. If we have to go through official suppliers, you would have thought you'd get a better deal."
The Warehouse chief executive Mark Powell has taken aim at schools advising parents where to buy stationery and uniforms. He said he'd been approached by a North Shore parent "absolutely livid" at a school's refusal to give him a stationery list, telling him instead said he must shop online at Office Max.
It was a trend the retailer had been noticing for the past two years with school notes being sent to parents. The tone of the notes this year seemed to be "far more restrictive", Mr Powell said.
"They're saying 'you must shop with OfficeMax'.
"There's nothing wrong with schools having programs and being upfront with parents [and saying] 'if you shop with so-and-so retailer then the school gets a reward'.
"I don't see anything wrong with that as long as they're giving them the list and making it clear they can shop where they like."
Parents should have choice, he said.
"We are concerned that some schools are starting to restrict parents' right to choose where they shop, and that this is causing financial pain for many families."
It's big business. The retailer estimates that during a six-week period at the beginning of the year the market does $31 million in sales.
Office Max's education and retail general manager Suzanne Flannagan said more than 400 primary and secondary schools had registered their stationery list on the company's website. Her company had raised $860,000 since 2007 for participating schools.
However, it was left to schools to decide whether Office Max through its MySchool program should be a sole supplier to parents.
"Many schools see this as a vital fundraising platform which requires no additional school resource."
Principals' Federation president Paul Drummond said "preferred" school/supplier arrangements were fairly common.
It wasn't a great financial benefit [to small schools] but the real benefits included parents being saved the hassle of tracking down each item, students having the right gear on the first day of school and quality.
However, best practice should include giving parents a list should they decide to find cheaper deals themselves, he said.