2nd hand shops, flea markets (online and normal ones) and when I want a new kit Ebay or a online retailer. But costs for a new one of these are around 30-40 euros, 2nd hand 3-10 euro. It is a bit hit and miss though, as you never know what will pop up. Could be I find none till July, or 3 in January. I'm aiming for 6-8 of these. The small oil tank makes a good one for behind any building in almost any location, I just do those in between for fun.