In the following post, there is a video where Graham tests the results of three different microphones ranging in price from just under $100 to $1,000. The mics used were:
AKG C414 ($999)
Shure KSM 141 ($399)
Shure SM57 ($96)
The tests they did were to record the same guitar and player, playing the same finger-picked music. The mics were all positioned the same and Graham gain-matched the recordings to make sure volume differences were not a factor in judging one against the other.
You might also want to read the comments below the post for some interesting insight from others. The point of this was not only to show how different the results of different mics can be, even when recording the exact same thing (useful in itself to perhaps add dimension and variety to your mixes), but also to highlight the fact that you can get useable and even really good results from a mic costing ten times less than another (I guess it's more correct to say costing 1/10th the price - whatevs:)).
Anyway, check out this video if you do music recording. Very interesting.
I'm going to keep using my Shure SM81 to record acoustic guitar though. I'm hooked;).
See Graham's video here.