Amazon offers Prime members the Tripp Lite 3-Outlet Surge Protector, model no. SK3-0, for $5.99 with free shipping. (Non-members can spend $35 to qualify for free shipping; otherwise, it adds $6.23.) That's the lowest total price we could find by about a buck. It features an AC suppression rating of 660 joules.
Update: This item is now shipping in one to three weeks.