Hmm... I don't have personal experience with either of those, but neither of those look too promising (the cheaper of the two just looks like a photoshopped iPod shuffle). Now, if your plan is to just plug one of those into your existing cassette adapter, you could give 'em a go and post your results here for the rest of us... but if you don't want to use the cassette adapter or a better solution that will wire into the stereo, you could look into a Parrot car kit. They have several different types for several different budgets. Again, I don't have any personal experience w/ any of Parrot's products either, but have read a lot of good things about them.
http://www.parrot.com/usa/products/b...ee-car-kitsHTH