Amazon offers the Tripp Lite 8-Outlet 300-watt 550VA Desktop UPS, model no. INTERNET550U, for $49.99 with free shipping. That's the lowest total price we could find by $9. It features four outlets with battery backup and surge protection, four outlets with surge protection, USB, and LED indicators.
Note that although it's currently out of stock, it can still be purchased at this price with an estimated in-stock date of May 12.