Following the other deal that expired very quickly, it seems that a lot of people are looking for cheap masks.
Not affiliated with the seller, but it's the cheaper I found on ebay.
Alternative seller (I bought from this one Monday and received it on Friday, but the bulk buying discount is a bit lower) : https://www.ebay.com.au/itm/50x-Disposable-Mask-Face-Masks-A...
Both are located in NSW, couldn't find a cheap seller in VIC.
And if you buy them, please have a quick search on how to wear them properly ;)
Edit: Price now $14.80 (down from $15)