A local small farm/hardware/garden chain store had 40# propane tanks on sale for $35 and I decided to get one. They were out so I asked for a raincheck which they have done in the past but today they gave me that deer in headlights look. I could hear the them talking about it and they decided they did not want to go all the way to the service desk and fill out the raincheck so they asked me if it would be OK to substitute the 100# tank. I said OK and they marked it down, the checker questioned it and called back so one of them had to come up anyway!!
Pretty good deal......100# tanks normally run about 80 bucks. Sometimes I find them on sale in spring closeout for 65-70.