Lovecc1020 via eBay offers this LED Incoming Call Flashing Light-Up Case for Apple iPhone 6 Plus in Gold, Green, or Blue for 99 cents with free shipping. That's tied with our mention from a week ago, and outside of other eBay sellers, the lowest total price we could find for a such a case by $5. It's designed to light up using the phone's LED.
Of note, the case is also available in Pink for a few cents more. Expect two to eight weeks for shipping.