In order to play music and really keep your class engaged, you need to have a quality sound system. The four criteria that are important for your music player is that it is portable (and thus small), can run on battery, has a remote control, and is able to fill your studio with rich, quality sound. We recommend spending around $70 or higher on your stereo equipment as spending any less will most likely not get you the type of system you want. CNET gives great reviews about several very good sound systems that are reasonably priced.
We recommend the Logitech S715i (which you can find at Amazon for $94) or the Philips DS1155 Docking Speaker (which you can find at Amazon for only $70).