Asus GX-D1051 5-Port Gigabit Ethernet Switch for $9.99 shipped after promo code EMCJHJA33 and this $10 rebate.  Here is a screenshot before the $10 rebate for your reference.  It features built-in power-saving, and supports full & half duplex modes.  Most places have it for about $19 after a similar $10 rebate.