Price: Ebay is a wonderful thing. After shipping I paid $122 US for both the Cardo helmet system and the adapter.
Performance: Crystal clear. It has a wind compensating mic, a speaker that turns up automatically based on wind noise, has no static what so ever, comes with built in rechargeable lithiom ion batteries, manual volume control, and answer/end call button (all on the helmet unit).
My phone can be set for auto-answer when the adapter is plugged into the 2.5mm headset port and I have successfully carried on conversations up to 80mph. Aside from trying to hear over the wind noise of my helmet I have had no complaints. The people on the other end had no idea I was even riding on my bike. Keep in mind I ride a sport bike so you cruiser fans with the big windshields will probably get better results.
My over all opinion? Worth every penny. I put my cell phone in my pocket and leave it there. If I need to call someone I use the voice dialing that is activated by the call answer/end button on my helmet mount. When someone calls I wait until the phone picks up and start talking. No taking the hands off the R6 at any time (except to push the call button). The only drawback I have had is the volume. It turned up so loud the first time that I was wincing in pain. I adjusted this by using the manual volume control to turn it down and everything was good.
I have had the system for 3 weeks and have only recharged the batteries once (and still haven't seen the low battery warning yet). How's that for reliability? They say talk time is approximately 7 hours. Even a teen age girl would find it hard to out last this setup.
Bottom line: You want hands free communication for your bike? Cardo Bluetooth is definitely the way to go.