The Wave Scanner gadget is indeed included with the Casual Trader plan; however, there are some limitations compared to the Trader and above plans. More specifically, the advanced filters are not available with the Casual Trader plan, and each scan is limited to searching for one wave set up at a time.
Our reference guide provides a comprehensive guide on using the Wave Scanner Gadget.
Also, an article on our blog provides some excellent guidance on how to get better results with the Wave Scanner Gadget.