I just got a job doing 3rd shift grocery stocking, usually they don't allow earbuds but there's no customers so everyone does it anyway.
I'd like to get something ~$30 or less (I don't really care about the sound quality so much as long as it doesn't sound terrible), and battery life lasting at least 8 hours. Wireless because I don't want the wire getting in the way of anything or feeling weird down my shirt.
Get a decent credit card and milk the warranty service they offer.