Music/Sound System Help Please!?

Ok so every summer I go down to the beach and juggle my soccer ball with me and some other friends. I always liked the idea of juggling to music in the background because it changes the mood and environment. To cut to the chase I'm looking for a good sound system somewhat like a stereo I guess that I can plug my ipod in at the boardwalk where I juggle. I just want it to be behind me while I juggle like on the sidewalk. I don't want it to be quiet, I want it somewhat loud and I guess it will need to use batteries unless you guys know some other way. Any suggestions? Please put links down to websites with what I'm describing so I can make my choice. Please keep in mind that I don't want it over $120. Thank you