I can't believe what they want on ebay for old petrol tins, I started collecting them 10 years ago to use at work when I had a modern tin rust out and leak on me. I glean them from sidewalk cleanups mostly and the odd garage sale. I just toss some fuel/oil in them and stash them away for the future. The round ones I use for straight petrol and the little 4L square ones for 2-Stroke, that saves confusion.
Sorry I missed the swap meet, would have been a good excuse to take a ride up the Brisbane valley. Not that a biker needs an excuse but it's always better that way.