Instead of a USB mic, look at an affordable interface and standard mic. Here's why:
1) USB ports are a valuable comodity in the studio, as there are never enough. So why waiste it on a single mic when that port could be used for a multi channel interface instead?
2) If you have an interface with an XLR or combi jack (XLR or 1/4" in the same jack), you could use it for any mic you can borrow from a friend. It wouldn't have to be a USB mic.
3) SM57's (THE industry standard mic) sells for around $50 used, and you'll always find a use for it.
Most of the sub $500 range interfaces come with some form of recording software and a full suite of extra plug ins. Plus there are also a couple of bundles out there that include not only the interface and software, but a mic and headphones as well.
For example: http://www.sweetwater.com/store/detail/AudioBoxStu/
While not necessarily the best gear going, it is good enough to let you do some pretty amazing stuff if you put your mind to it.
Just for fun, here's a vid on mic'ing your full band using one mic and simple interface, in this case Mbox Mini with ProTools Express, using a Behringer B1 condenser mic. Total price, less than $300 NEW! http://www.youtube.com/watch?v=1o9L7agaluo
Whether you like the song is irrelevant. This is about showing that you can do it, with minimal outlay of finances.
Skip the USB mic. Just my "dos centavos".