If a student was going to school with an old shirt or worn out jumper, they could become the object of ridicule and their self esteem could plummet, he said.
"In winter we often see kids off school because they can't get their school uniform dried in time for school the next day.
"If they only have one pair of pants or one shirt and it's not clean and dry, they can't go to school."
He said that while schools talk about the importance of uniforms in helping form identity, if that sense of identity puts families in debt then the system isn't working.
"The lack of the right school uniform shouldn't bar you from education," said Haua.
"I don't understand why there can't be generic school uniform options for all schools. Just because someone comes from a family who is financially struggling it doesn't mean they shouldn't have equal opportunities and equal rights."
The huge price difference is largely because New Zealand schools have bespoke uniforms with only one supplier.
In the UK it's common for schools to choose a generic design, which parents can buy from chain stores and supermarkets. The schools have embroidered badges that can be ironed or sown on to uniforms.
Green Party MP Catherine Delahunty said schools needed to offer far more flexibility.
"Schools should be able to have uniforms, but parents and students should be able to make a decision around whether or not they choose to wear them," said Delahunty, who led a campaign against uniforms at her own school when she was 15.
She said enforcement of uniforms was a waste of teachers' time and a means of social control. It also contributed to financial hardship for many families.
"Poverty is at a huge level in this country and the cost of uniforms just increases the pressure families are already under," she said.
A recent survey found that nearly 70 per cent of families would prefer there to be generic alternatives to the bespoke options that are mandatory in many schools.
The survey, commissioned by Postie Plus, revealed that some families were sacrificing food, electricity and personal hygiene items to pay for uniforms.
And that is only one cost when you add in digital devices, shoes and stationery.
Postie Plus has launched a range of generic school uniforms with prices similar to the UK counterparts, but not all schools allow generic options.
Brent Lewis, principal of Avondale College, said it would be a brave government that tried to enforce any sort of nationwide uniform policy.
"They'd have the school boards and communities to contend with," he said.
He is proud of his own school's bespoke uniform and said there were many factors that made uniforms the best choice for his students.
"Uniforms are a huge source of pride and identity for schools."
Avondale College is one of the biggest schools in the country, with nearly 3000 students.
Lewis said the quality of the bespoke uniform made it worth the money in the long term.
While the Avondale College uniform is at the higher end of the price scale, Lewis said the school made sure each student had access to the uniform.
"We have all sorts of arrangements available. If people are struggling to afford a uniform, they should engage with the school in the first instance."
Lewis said uniforms helped create a level playing field for students from diverse backgrounds.
"Its aspiration is for every kid at our school to have a great school uniform and be proud and confident in wearing it."
Uniform policies differ from school to school. The code is set by the boards in consultation with parents and the community.
David Wales, acting head of sector enablement and support for the Ministry of Education, said schools should communicate very clearly with parents what their requirements were - but it was up to parents to make informed choices when deciding which school to send their children to.
"Parents should ask about the expectations and likely cost of school uniforms before they enrol their children."
