http://www.amazon.com/Kinivo-BTH240-Bluetooth-Stereo-Headphone/dp/B00AWIPITSI use these Kinivo BTH240's...
never heard of them before purchasing, but read reviews on fitness forums and decided to take a chance since they are only $25
Sound quality is pretty good. Nothing fancy, doesn't hit super low bass but I'm not necessarily looking for that when I'm lifting... I don't do any cardio so I can't review if they stay on well while running.
They keep sweat out of your ears and are very comfortable, although if you have a large head you may want to look elsewhere... I would consider my head size average lol I'm talking that Mike Ditka-sized head
Battery life is awesome... I charge these bad boys once a week and am at the gym 5 days for 2 hours at a time... never died on me. Maybe once they get older the battery will start simmering down, who knows.
IMO, can't go wrong with these for the price. Bluetooth, too!
Purchased. Look legit.