Quoting david :
> I think what you need is to use cheap computer mics, not music-quality
They do require a sort of preamp, but every soundcard which provides the 5V
supply voltage for the electret capsule will have such a preamp.
These 5V mic supplies are usually in every "normal" soundcard. I'm not
talking about the ones you buy from the store but the ones which are
included in your computer by default.
HAMs will like a bit of soldering, so check this out:
It includes information on how to connect the capsules and information on
the voltage provided by mic inputs on soundcards.
Electret capsules can cost < $1 so it should be cheap enough for your needs.