Hi Tia,
these days with the popularity of Transformers there is good likelihood of finding licensed items at places like Big W, Target and K mart though if there is anything out there right now that meets your needs I have no real Idea.
A year or so ago there were some 'classic' tin lunch boxes available at Kings Comics in the Sydney CBD however they were of very low quality construction.
There is a new chain of stores in Sydney called Zing. They are a pop culture store and may be able to get something like that in for you, they are owned by EB Games so if you have a local EB they might have something, though EB traditionally only stocks game related merchandise.
Another alternative would be show bags, though those things don't usually stand up to the rigours of school

.
Perhaps if you can't find anything right now, wait till the new year school stationary sales start, you are more likely to find merch like that then, even at Officeworks.
Hopefully you're successful in kitting your son out with some cool gear!