You get what you pay for, generally. The Nady mics work, but they aren't the best in their price range. I have 2 scm900's that work OK, but I'm told I got lucky on getting a pair that sounds close enough to use in stereo.
They are stock Chinese mics packaged for Nady. (shrug) They are nothing special at all. I like my SP C-1's much better. I'd never ues the Nady's for vocals, either- not with the other mics I have around. I dunno- I try them for other people's voices but they don't like mine at all.
YMMV, but the Nady mics (and all the stock Chinesem mics) are a step UP from Radio Shack, but still the bottom of the barrel.
Take care,
Chris