It seems like a gaming headset is a cheap option for my radio, considering I have a 3.5mm to XLR adapter, along with an adapter for the Yaesu mic input (from XLR). However, what I'm not sure about is power requirements for the microphone on the headset. What microphone element type should I be looking for in a headset? Has anyone used a gaming headset with their radios with any success? Thanks.
This answer has details that are not appropriately relevant because it does not match the actual features of the FTDX3000 microphone port. Update to come.
I'm not familiar with the FTDX3000, but PC headset microphones, and most microphones for handheld radios, are both electret microphones. Electret microphones require a small DC voltage across their terminals (not on separate pins) to operate, because they have an internal amplifier circuit. (The scheme for PC microphones is called "plug-in power".)
So, the good news is that the microphones themselves should be electrically compatible. The bad news is, you may not have the right cables to hook it up, because XLR microphone connections typically do not have "plug-in power"; they have "phantom power", which is much higher voltage and connects differently. Therefore, it is possible that one or both of your XLR adapters has internal capacitors or transformers to block the other power standard from interfering.
So, it might just work. If it doesn't work, figure out a cable adapter that is not going through XLR. As long as the right two pins are connected, with the right polarity, the microphone should work.
Some more details in case of wiring confusion: The PC microphone plug-in-power standard nominally separates power supply from microphone: on the TRS plug/jack, the tip is audio, ring is power (+3 to +5 V) and sleeve is common for both. However, most microphones just wire the tip and ring together to go to the electret, and many microphone jacks also combine them (with a capacitor for audio coupling and a resistor for current-limiting the power output), particularly in order to enable stereo input (so the tip and ring are left power+audio and right power+audio).
The radio will probably not have this extra feature, and have a single contact for audio and power. This is OK — just use the tip contact of the headset microphone plug for the side with positive voltage, and the sleeve for the other.