Hold your horses on the MOTU controllers and Mackie control surfaces, guys. The OP wanted.... a mic. Under $200-$300
hens000
It would help if we know what you wanted to accomplish with the microphone.
In general: A microphone will need a pre-amplifier - that starts with a Griffin iMic and goes up from there with USB and Firewire digital audio interfaces. A condenser microphone will probably need 48V phantom power to operate. The Griffin iMic and the lowest priced interfaces do NOT provide this. You can either get a more sophisticated interface ($200 and up roughly) or you can use a mixer that has moc preams and phantom power.
There are a couple of microphones that have USB connections built in -- that is, they have their own preamplifier and A/D convertor, and run on 5V power from the USB buss. These are adequate,but there are several problems. The sound is never going to be as good as a dedicated preamp or interface with its own mains supply. The USB microphone will be utterly useless away from the computer (no analog output) and you likely can run one, and only one, of these microphones on one computer (no micing the voice and guitar at the same time, or drumset, or 2 voices...)
Anyway: Please use the Search function of this forum, we have covered this subject many times.
And: Do your homework before deciding. Hot the newsstand or library and read Sound on Sound, Computer Music, Recording, Electronic Musician, Future Music and Keyboard magazines. They have many articles on just these subjects, and Sound on Sound's current issue is all about recording vocals.
Thanks
Trevor
CanadaRAM.com