A dark-colored bowl filled with water is a very easy acquisition, if you don't already have a dark bowl. Dollar stores, thrift stores, etc., frequently have them for cheap. You could also get a cheap frame and black paint to make a dark mirror. Those are two options for scrying in a manner similar to a crystal ball.
You could also explore other methods of divination, such as pendulum, cartomancy (cards -- they don't have to be tarot but you need to have some idea of meaning, and being unversed in the matter I have no real helpful advice), tea leaves, things similar to casting bones (have a chart, and scatter a handful of objects across it), reading smoke, signs in nature, reading auras, flipping a coin ...
You could be creative and make your own method.
Others will have differing opinions and advice, of course. Just know there are other options to a crystal ball.