I had a terrible time trying to find the large cookie tin. Ended up buying one full of cookies at wal-mart. It was $9.88, and the lamp kit was $6.47. Still cheaper than buying a water heater and it is working great. Now, if I can just stay out of those cookies!Here is another great source if you decide to do it yourself. It can be done less than $10. Great step by step instructions. Good luck
https://www.backyardchickens.com/a/cookie-tin-heater-for-water