Keyjump via eBay offers the 16 LED Flash and Fill-In Light for Smartphones and Tablets in Black or White for $2.71 with free shipping. Outside of other eBay sellers, that's the lowest total price we could find by $2. It's compatible with most smartphones and tablets with iOS 6 or later, Android 4.0 or later, or Windows Phone 8.

Note: Expect three to eight weeks for delivery.