contact mics

[Stephen Handley <shandley@xxxxxxxxxxxxxxxxxxxx>]

all this talk about contact mics has piqued my interest.
what exactly is a contact mic?
how is it different from other microphones?

the radio shack cardiod mic $19 joint definitely has its limitations :).
but, then again so does my wallet.

what's the least i should be looking to spend?  could i build it myself 
for cheap?

thanks for any help,
stephen
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Ranger: New Mexico Game and Fish Department
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