Microphones

For some uses it may be very important that the frequency response of the microphone is flat--most consumer mics have peaks in their response that distort the importance of certain frequency bands. The cheapest solution I've found is the Behringer ECM8000. It's not a great recording mic, since it's designed specifically for measurement and nothing else, but it would work well with this application. It's a professional mic, though, and needs a powered preamp between the mic and the computer, which can add a bit to the cost. If accuracy is your concern, though, it's the best low-price option.