Belkin 5-port splitter + Aux Cable for $5

MacMall is offering the Belkin RockStar 5-Port Multi-Headphone Splitter + Aux Cable for $5 total. No coupon needed. You can buy as many as you like. Free shipping with an order of $35 or more, otherwise you have to pay shipping. Only one color scheme is available through this offer. This is an unpowered splitter, so the number and type of headphones attached will affect the output volume.

If you want other colors or have free Prime shipping, the prices start at $8 at amazon.com with a very solid 4.7 out of 5 based on 742 customer reviews.