Maybe something like the square ones here?
I don't know of any local sources for them offhand but I remember seeing them in some dollar stores.
The ones I saw were not very heavy gauge and I didn't think too kindly of the plastic lids but they were not really all that bad (I tend to be fussy).

Maybe if you check with a local discount store they could tell you the cost to source them for you.

May set off to explore without any sense of direction or how to return.