Since you're looking just to make a webseries, I recommend a USB condenser mic. The ones with good quality range from $90 to about $150. There's no reason to spend more money on a professional studio microphone when animation is what you would like to do. The quality of the following USB microphones are still pretty amazing when it comes to voice and instrument recoding.
Here's a list of some USB condenser mics that I recommend:
1. Audio Technica's AT2020 USB Condenser ($115) [My STRONGEST Recommendation]
2. Samson C01U USB Condenser ($100)
3. MXL 990-USB USB Condenser ($100)
The best free software for mixing and sound editing has to be audacity. I have a post on it.
http://octobeats.com/?p=159