Right now I have an MP3 player hooked to my Sony stereo down in the cabin. I recently picked up a Sony remote head at a West Marine Store that was closing. West Marine Price: $130. Store closing price $12.
I'm going to remove the old Raymarine Wheel pilot head from my Navpod (no longer used), put the Sony Remote in it's place along with a mini-plug extension run back down below to a y-connector wired into the stereo. Now I can unplug my MP3 from below, plug it in at the helm, flip through tunes and control the stereo without having to go below, all for under $50.
Sony Remote Head $12
Mini-plug extension: $15
12v power plug for MP3: $19