I have a genuine 29 watt charger but my USB-C to Lighting may or may not be genuine. It didn't come in a box. I've never gotten the message on the screen that says it isn't an approved cable but it isn't worth taking the chance. I have to be at the Apple Store tomorrow, I'll spend the $25 on a real one.
Wise choice. When something is so good at killing devices they're literally making emergency changes to the USB C protocol (http://www.gizmag.com/usb-c-update-dodgy-cables/42786/) you know it's a good idea to shell out those extra few bucks.