I don't want to barge into your thread, but I'm looking for one of these too and they're impossible to find. It seems like they're out of stock EVERYWHERE. I called all of the car audio shops in town here and no one has one in stock. It's very frustrating.
I called my local Car Toys and they said they didn't have any in stock. Then I went into one during lunch a day later and spoke to a human. After listening to him explain why it wouldn't work in my system for 15 mins, he looked in the computer and found one in a store across town. I recommend going into a store to find one. The one I found was opened and I talked them down to $78.00.
Also try doing a Google like this...craigs list: Alpine KCA-420i
There are a number of them for sale on CL. About half the people are willing to ship if asked.