Removeable Stereo mics that come with digital recorders

["ndbdxr" ndbdxr]

For example, I just bought a 'New SONY ECM-DS70P ELECTRET STEREO MICROPHONE' 
off of e-bay (for $.01). 
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220487216324&ssPageName=STRK:MEWNX:IT

I bought it to try on my Olympus DS-30, just to see if there is any difference 
in performance to the one that Olympus included.
And it just got me wondering: Has anyone ever found one model/type of these 
little units to be any better than any others?

I plan to get a longer extension cord for it, etc. so that it can be mounted 
outside, etc.
There are a ton of these little stereo mics out there; and I was curious if 
anyone has found any to be worth tracking down?

If I can find a few more at these prices, I may do some comparison tests 
myself!  :)

Any advice would be appreciated, and thank you to all who provided great 
responses to my last post!

...I'm going to go try and install a MEMs mic from Sparkfun into the last 
Heterodyne bat detector I built. This mic is tiny - wish me luck!

Thanks in advance,

Al