Most voice acting work simply requires you to record the sound files and then send them off to the modder and they process and master them, at least that's what I do in my mods. You need a good microphone and Audacity at the very least. Myself, I use a Sure SM57 with a windscreen through an 8 channel Firepod into Cubase software. That's only because I use that rig to record my entire band. It works out very nicely for voice work. If you use a desktop mic you need a really good one. You can pay anywhere from $60-$600.