Hey MPx-220 users..
I found a real gem that's not only cheap, but works perfectly with my MPx-220:
http://www.gadgetfreeks.com/98308g-syn8598v.html(Note: The model I got from another source was the SYN8597, but the above link also mentions that model too, and they both say they work with the same V60 series, so I would think the 8598 is just a slight update to the one I have)
It's an original Motorola-brand hands free kit with these features:
1) Great sounding 3-watt speaker.
2) Your phone will automatically switch to the "Car" profile when using this - so you can customoize all the volume levels.
3) All sounds come from this device, including the "Say a Command" prompt and even playing back voice notes, playing music files, and I bet any other audio app, such as a voice-based GPS apps.
I kinda like this solution over bluetooth because it will also charge your phone
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-John Cody
UPDATE: There seems to be some excessive background noise issue when people hear you using HF kit. I tried using an external mic, but it wasn't the official mic for this kit, and the problem wasn't any better - sorry for this possible bad news