So, why not buy a $2 mic? http://www.dx.com/p/mini-clip-on-microphone-7080

You can't. Unless you get something like a Mixamp and TurtleBeach chat cable to split both inputs. Very costly of course.

Otherwise, the Gold Headset is your option. It sounds comparably worse on all fronts than the M50 though.

It's a little bit more complicated than you think.

The issue is, the PS4's controller only allows the user to either send chat audio to the headphone or game audio, not both simultaneously.
So splitting the connection to the controller would just result in either you getting game audio or chat audio, whichever you select. You can't select both simultaneously. Why? Ask the idiots at Sony. The PS3 allowed this, but not the PS4.

There is another work around which you will have to perform every single time you start the PS4 though, much cheaper than getting a Mixamp and TB chat cable.
I personally don't chat anymore on the PS4 as my preferred setup was to clip a bluetooth headset onto my shirt and pipe all audio into my headphone like on the PS3. So until Sony fixes this, no chatting for me then.