When the majority of your content is auditory, I think you really need to nail the audio quality. Acceptable audio quality doesn't have to be expensive. I would suggest buying a new mic, what ever you can afford. Next, I noticed a lot of echo in the audio. I assume that may be from the room you are recording in. If you record your audio separately from your game play, you should consider building a sound booth. There are a bunch of cheap DIY sound booth videos on youtube, you basically line a box with foam and speak into it so that it eliminates echo.
Anyway, you don't actually need to go crazy, but seriously consider doing something to increase the audio quality.