Hnads down JayBird X…expensive but the sweat warranty, USAT discount, and unobtrusiveness make them enjoyable. For soemthing you will use often, treat yourself
+1 for the JayBird BlueBuds X (http://www.jaybirdsport.com/bluebuds-x-bluetooth-headphones/). Well outside the OP’s stated $50 budget but well worth the money in my opinion. They stay in your ears regardless of activity level, sound good (to me anyway) and so far have been impervious to sweat.