I know this maybe a two month bump, but coming from a let's player standpoint, I have to tell you that a microphone will always pick up keyboards and mouse noises so long as you don't edit the audio. You really should try out a program called "Audacity" to remove any background noises, rather than spending 100$ on equipment that is literally just an expensive version of what you had before.
Then again, you probably decided to quit already, but I thought I'd give my own advice.
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