Unfortunately, there is no way to buy the application because no info is provided in terms of contact, download, or payment methods. The software along with its developer is mentioned on a website, but that's it. There are no contact options provided. I also belie that Barrel Jackpot is now considered a discontinued application that won't be available for purchase any time soon.
There is a forum with users that use apps from the same category Barrel Jackpot was. Access it and read on their forums or ask their help.