I just use cheap headphones. I still have a pair that came with one of my phones that are held together with electrical tape that I use when turboing outside (with an mp3 player clipped to my jersey/shorts).
I have a phone holder for bikes but don't normally use it on the turbo as I have the mp3 player. If it makes you feel better I killed one of my mp3 players after dripping sweat on it too. So that's in the car now basically acting as a small USB stick.
I just use cheap headphones. I still have a pair that came with one of my phones that are held together with electrical tape that I use when turboing outside (with an mp3 player clipped to my jersey/shorts).