USB-C can be electrically compatible with Displayport. So a cheap 5-dollar adapter should do the trick.
http://phandroid.com/2016/02/02/usb-type-c-incident/
Apple's prices are a lot to pay for a passive component. But chances are that they'll do it right.
I personally will look at cheap and reliable testers (http://phandroid.com/2015/11/04/best-usb-type-c-cables/) and buy those.