I have made a fairly simple and cheap slot machine. The payment can be adjusted to use any item that stacks to 64, and the prizes can be anything you can put in the dropper. It uses some hopper/dropper randomizers that I first saw on HiFolksImAdam's YouTube channel. This video was made in 1.5.1, but the slot machine still works in 1.5.2. Also works in multiplayer.