Depends on the mics you already have. Start with the cheapest stage mic you have and go up from there. Most harmonica players usually have their own mic. I like to run a cheesy mic (with limited response) thru a really small guitar amp, and then mic the amp. There ain't a whole lotta range to a harmonica so unless you really want a hi-fi solo, go for the grit.

If you're going for a folky Dylan type thing, use a large diaphragm and some space. Also have the player hold the sides of the harmonica, not "the blues guy cup around the thing"

I believe allot of cats use an astatic mic with their microphone.

Anyone?

Mixerman

Every blues/rock harp player I know uses an Astatic mic. They are cheese in the extreme and add tremendous overtones to the harp. I usually record using a large diaphragm condenser (like my Rode NT1) about a foot away from the speaker of a Pignose or other smaller amp and get a great "in your face" harp sound. A 57 or 58 will work but not like an Astatic.

And the Astatic has a volume control on the mic, I believe. That makes it easier for the player to adjust his/her level while playing.