Another decent USB mic for your budget: http://www.gak.co.uk/en/akg-perception-120-usb-plug-and-play-microphone/39707
Review here: http://www.soundonsound.com/sos/may11/articles/akg-perception-120.htm
Or if you went for a mic with an audio interface (like the Behringer one noted above) any of...
If its just for podcasts or something like that then a USB mic like the blue snowball would be a good bet.
If its for recording instruments or vocals then you also need to think about how your going to connect it to your PC as you'll need some sort of audio interface and if its a condenser mic...