I have a Cobalt Co7 mic and really like it. (It is the model just below the Co9. They probably have the same capsule.) It sounds very close to the SM58 and every bit as loud. It has just the slightest bit of coloration, but not enough to complain about.
A Co9 for only $30? That's a decent bargain. You won't be disappointed. It would be great for the practice room or gigging in the bars. Now, if you want it for critical studio recording? Perhaps you should not be shopping for a $30 mic.
I may order one myself.
Critical studio recording, I guess this depends on the duty the mic is to perform. If it is as good as a SM58, then for drums, amps, ??, etc. I am not sure what price as to do with it (other than, they are a good deal or they are not). With Shure mics there is a up charge for the branding, therefore price is not always 100% indicator. That is why I asked if they compare to a 58. $30 (Amazon has these mics for $78) for typical 58 duties seems like a deal.
If the two mics are close to being the same, I can get 3 EV's mics for the price of one 58 with the same results, I think that is a deal. As stated, if they are not close, then the price is irrelevant in this case.
When I made that statement about studio recording, I had vocals in mind. But now that you mention it, the Co9 would indeed do well on a snare or something like that. My Co7 is every bit as rich and natural sounding as a 57 or 58. It just has a slightly different character or flavor to it. The key word being "slightly". I would guess that in a blind A/B test, most folks would be able to notice a difference in sound, but would not be able to identify which is which.
Again, I am making the assumption that the Co9 sounds the same as the Co7. I don't actually own a Co9....................yet.