Vader2k
It's confirmed! You can most definitely run seperate game/audio chat with mic + other features like mic monitoring, capability to play your own music through your headset, feed any audio you want to your peers, etc.. all for around $100.
What you'll need is a behringer 802 mixer (not usb version($60 new)), Sabrent USB sound card ($6), xlr input microphone (around $20), Hosa 1/4 TRS to dual TS 1/4 Y cable (from AVR to mixer($5-7)), Hosa 3.5mm to 1/4 stereo (mic input on Sabrent to mixer ($5-7),3.5mm to 1/4 Y cable (Sabrent HP out to mixer (around $5)),
I would buy a couple extra 3.5mm to 1/4 in Y cables so you can plug things like your phone, mp3 player, or CPU into the mixer too. Also, get a few 3.5mm to 1/4 adapters so you can transform your cables if you need to.
From the HP jack on the AVR I run that to 5/6 so I can get eq's on my game audio. The single 1/4 to 3.5 you run from FX Send to the mic input on the mixer essentially acts as a audio input for the PS4 so whoever you're chatting with will be able to hear anything that you twist the FX knob up on; maybe like a playlisy for a raid.. except it will be mp3 quality instead of coming through your mic. The 3.5 to 1/4 y feeds into stereo aux and the aux return knob will make chat louder or softer... and of course you'll use a kick ass pair of cans from the HP out on the mixer (which you'll obviously need a 3.5 to 1/4 adapter for) to get all of your audio. I'm typing this on my phone and left a lot of detail out. It's actually quite simple and we'll worth the money. Hope I was able to enlighten you on getting the best possible audio experience from your receiver! PM me if you have any questions or want me to make up a shopping cart on Amazon for everything you need.