I bought a Sony ECMCS3 lavalier mic, but I can't use it with my Mac because it's not powered. What do I need to buy to make it work? Ideally it should be portable, and cost less than $30.
If this is not possible, what are some good options for amateur-quality mics for video recording?
You could get something like this for your existing mic: http://www.ebay.com/itm/MONO-TO-STEREO-MICROPHONE-PLUG-IN-POWER-BATTERY-MODULE-/280567421956?pt=UK_MusicalInstruments_Other_Pro_Audio_Equipment&hash=item41531f1c04
or the mono variant: http://www.ebay.com/itm/3-5mm-MONO-JACK-MICROPHONE-PLUG-IN-POWER-BATTERY-MODULE-/270787690564?pt=UK_MusicalInstruments_Other_Pro_Audio_Equipment&hash=item3f0c344044
or in a more kludgy box: http://www.ebay.com/itm/STEREO-MICROPHONE-BATTERY-PHANTOM-POWER-PREAMP-MODULE-/270620193225?pt=UK_MusicalInstruments_Other_Pro_Audio_Equipment&hash=item3f023871c9
or, not directly what you're asking, but nevertheless a solution to your problem and within budget: http://www.amazon.com/Audio-Technica-ATR-3350-Omnidirectional-Condenser-Microphone/dp/B002HJ9PTO This simple lav has a power supply, meaning it doesn't need plug-in power.
If you are happy with basic soldering they are straight-forward to make cheaply as are no more than a battery to supply DC power and a capacitor to block the power getting to your PC
One typical circuit can be found in the following topic
Could you not use a small portable recorder such as the Zoom H1, then transfer the recordings to the mac via USB? Zoom H1
You need something that can supply 'plug in power'. Most recorders can do this so there are not many devices around. Often people make their own.
There are some on ebay for £15ish. I think your mic is stereo, so make sure you get one capable of that.
