First, it's a "cable."
But anyhoo, since you guys are my both my bestest internet bros, and a bunch of truly stupid, stupid individuals, let me help you out...
When purchasing an HDMI cable (not that I've ever done that, I have a pile from work), the difference between the $6 HDMI cable and the $120 HDMI cable is... $114.
There is no signal degradation through a HDMI cable (unlike analog formats, like VGA, Component, RGB, etc). Either the contacts are touching, and there's some sort of wire between them, or they're not -- which will be quite obvious. Sure, the cheapies won't withstand as much bending and whatnot... which shouldn't be an issue. And $120 buys a lot (say around 20) of $6 cables.
But hey, you spent $600 on a new 4K UHDTV, and you want the best picture, and don't want to but the el-cheapo cable, right?