Academies have been accused of frittering away public money on "branded biscuits and USB sticks" while state schools are struggling to release cash for "essentials" such as pens and paper.
Zoe Lynch, a teacher from Wolverhampton, said the situation was summed up by the contrasting fortunes between her school - where teachers "have to beg" for materials - while a nearby academy has branded biscuits.
Ms Lynch told delegates at the NASUWT union conference in Birmingham that her head teacher denied her request for a new cupboard due to budgetary constraints, but that the school could provide a padlock if the caretaker was able to source an old storage unit.
She told delegates: "We have no budget for buying essential materials. So why can academies afford to pay for extravagant buffets when networking?
"Why can they afford branded marketing materials such as biscuits with academy logos on, branded pens, USB sticks?
"All this while the budget is held centrally by heads, and we have to beg for new glue sticks. I'm now down to one glue stick with no lid on - it looks like I'll be going shopping this weekend.
"Why is this money being held by the fat-cats and not used to ensure we have a world-class education?"
Delegates also heard tales of academies spending money on entering awards ceremonies and drinks for visitors.
The conference voted to conduct research into how multi-academy trusts and local authorities use their funding.