At this time, we're recommending the Audio Technica ATR35s as an inexpensive microphone, that delivers fairly good sound. You can get it on Amazon for about $25, and you may be able to find it inexpensively in your area as well.
We don't have a lot of opportunity to review inexpensive microphones, though, so if you find one you like and it works well for you, we encourage you to share it via the forums, and if you can, post a sample in the Show & Tell section so people can hear your microphone for themselves.