I just got the radio shack item and I already have the Jabra.
The radio shack is not really a "replica" of the Jabra. The Valley Stream, NY radio shack had plenty left and the guy looked at the coupon for a little bit, but didn't give me any problems. $2.16 out the door.
The jabra is more comfortable since it's got the gel piece. It stays in my ear better as well. The radio shack one has a large, round(couple of inches) base that's a bit more to carry around BUT the cord retracts into the base so that there is no cord to get all tangled up. The jabra one is pretty much just a cord with an earpiece at one and and a plug at the other end.
With both I hear the other person clearly and loudly. I had another oem product before this that didn't amplify and it was hard to hear the other party unless I held it in my hear.
I'm not that impressed with the microphone of either product. Both are about the same. In a car, the other person can hear you fine but it sounds about equivalent to the you talking on a bad speakerphone. It's obvious to the other party that you are on a hands free device. Still though, they can hear you find and have a very acceptable conversation even while driving 55.
Personally, I feel a LOT safer using a hands free device and I think it really makes a difference saftey wise.
At $2.16 or free after rebate, I don't think you could go wrong either way.
I'm going to keep using my Jabra (which I paid $20 for!).
Lex