Purchased from RPM (Revolution Performance Motorsports) on-sale for $124.95, regularly 139.95. They have versions for all current and recent Mazdas, with the jack to the stereo itself being the major physical difference. You must specify your car model, year, and iPod model at the time you order.
Installation took me about 2-1/2 hours since this was my first time pulling the radio in the 8. If I ever do this again, I'm sure I could do it in under 90 minutes.
This unit has a "magic box" between the jack that plugs into the stereo, and the iPod dock connector itself, that allows you to plug in a standard MP3 audio jack, as well as a Bluetooth xmitter (available for another $50). One nice thing about this unit is that it charges the iPod, wheras the Mazda unit doesn't. All the steering wheel stereo controls are fully functional. All standard stereo functions are retained, you don't have to sacrifice some other functions to use the iPod. Here are some photos showing some of the install details.
This photo shows where I had to locate the "box". I put foam rubber under and over it to isolate it from vibration. It's easily accessable if I want to plug in a 3mm "AUX" input (standard MP3) or the Bluetooth jack.

I used a Uni-bit to drill a hole here to pass the cable through into cupholder/console section. It emerges through that tiny pop-out piece. I drilled a hole instead of going close to the hand brake, to avoid chafing the cable if it rubbed against the brake mechanism.

Here we see the cable hugging the right side of the cup holder area and into the console storage bin.

And here we see the cable pulled out again and the dock plugged into the Nano.

The dash display with the iPod playing song number 1 on playlist 1. I suppose "EX" means external.

Here is the tool I used to remove the secret, hidden bolt that all RX-8 owners who pull their stereos know about sooner or later. It is a "thumb ratchet" attached to an 8" extension & 10mm socket. Note the rare-earth magnet near the tip- my bright idea to keep the bolt from falling. The problem is, the magnet was so strong that it stuck to every metal bracket under the dash! I discarded the magnet and used contact cement to glue the bolt into the socket while tightening. The thumb ratchet was a life-saver.

And here, for the first time to my knowledge, an out-of-focus shot of the secret hidden bolt. I could barely get my cell phone up in there with the flashlight resting on that little shelf under the steering column.

Also a real life-saver as a wooden case I had that is just about the same height as the door sill. I placed it next to the open door, then threw a 6-foot-long carpet runner on top of it. It provided a nice platform for me to lay on while accessing the hidden secret bolt.

Here is the Web page for the actual product :
http://www.therpmstore.com/product_info ... cts_id=142
I'm giving this product a "thumbs up" review. Recommended.

