Some of the first mics that come to mind are:
Core Sound (though I have found the binaurals to be too noisy for doing classical or unamplified jazz- haven't tried any thing else besides high end stuff)
Audio Technica 831
Full Compass has a ton of miniature mics that would be suitable for stealthing, some nice mini Sennheisers, Countryman, Sony, etc, check out their catalog,
http://www.fullcompass.com/Happy shopping!
Ben