Hi,
It's funny, these cost ?1 at my local Poundland too!
I bought one of these a good few months ago for exactly the same reason as you. I buy the 5lb bags of onions too and bought this to put the 'left over' onions into.
As well as keeping them as fresh as possible, not being full of holes like the onion nets means the bits of skin that fall off don't end up everywhere in the cupboard either.
I think our Poundland has balti dishes too, but I've not bought one since they seem a little flimsy, but that's to be expected for ?1