Clever (not really) marketing maybe? Can't win if you don't have an ECS board, so if you want free stuff, by default, you have to buy one of their boards. Guaranteed sales right there .
Today praxair quoted me ~$2 and airgas quoted me $4. Where the hell in the US do you guys live that you get it so low? If I could get it for <$1 I would fill it up every weekend and use 120L per month.