Groupon offers the Otterbox Preserver Series Case for iPhone 5/5S or Samsung Galaxy S4 in four colors (iPhone Carbon pictured), model no. 77-36355, for $29.99 with free shipping. That's tied with our mention from a week ago and the lowest total price we could find in either style by at least $5. This case is waterproof up to 6.6 feet and features a built-in screen protector. Note that it's not available in all style/color combinations. Deal ends December 26.
Note: It's not guaranteed for delivery by Christmas.