I know it's probably not what You're looking for, but normally, I use bluetooth "adapter", which allow connection of any "jack" headphones + additional microphone (different port). This way, I use my *non* wireless Koss Spark and any microphone I feel fancy - both wirelessly.

It's very adaptable to different scenarios - for example, You can as good plug-in "big" stationary speakers (through jack) and stream music from N900 via bluetooth, or catch sound from distance via microphone.

It's also *much* cheaper than stereo headsets, with many brand and no-name things available. Overall, they offer same sound quality, as it depends purely on earphones plugged to it - sound itself is carried digitally via standardized bluetooth profile.
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Of course, some people claim that connecting cable earphones to bluetooth "thing" isn't for them, as they don't like any inch of cable - yet, I like adaptability of such setup.

/Estel