This may help:
You can use bags, buckets, boxes, anything to grow potatoes just about as long as you know how to care for them and add dirt to give even more roots as the stems grow taller. You can also buy online reusable containers made especially for potatoes. Here is one idea to use free pallets to grow them. https://www.hometalk.com/2460971/how-to-grow-potatoes-in-a-pallet-container
Google, yard and garage sales, hardware and home improvement centers, nurseries, discount stores like Wal-Mart, Target, Home Goods, Ross, T J Maxx, Marshalls, etc.
I use an old bathtub to grow my tomatoes. Works great.
Don't havta ""find"" any. Just get a large plastic trash can & cut a bottom hole & there ya go. Any size trash can will work.