I'm confused what you're asking? If you're trade ding either or, trade the beats, if you're trading to get one of them, go with the iPod, or keep the bike. Beats are a waste either way. If I understood that correctly.
I have a bmx bike and I use everyday, why do you want to give yours up? I also have studios and an iPod but they are usually plugged into one another :/ It really comes down to what you can do without, the music or the head phones ...