Headphones while he works? iPhones are great for streaming music and podcasts while working.
I have these and am very happy with them: http://smile.amazon.com/Sennheiser-II-Precision-Enhanced-Earbuds/dp/B001EZYMF4/ref=sr_1_1?ie=UTF8&qid=1412827354&sr=8-1&keywords=sennheiser+cx300+ii
Sorry Paco, most of the people reading this thread are recommending headphones that they think are great for the price, but won't work with the Neo Hybrid case. There have been a few that would work. The Samsung ones nibiru10x recommended looks like they will. The red and black HTC ones posted here will as well.
My recommendation goes for the Sennheiser CX300s. They're $26, so a little bit more than your $10 limit, but sound great.
Try these out. Used to use the Samsung buds before they broke. Picked these up, and never went back since.