most stereo companies will NOT provide faceplates for decks b/c when they are stolen, they are typically taken without the faceplate. so... getting one from the company would probably be difficult.
i would say troll on ebay for it. you can probably pick up a face plate for your specific radio, as long as it isnt too old.
or u could post some want ads in the paper, or on some forums to see if anyone has a leftover face plate from a deck that crapped out on them.
if your buddy still has the original bill of sale, you might be able to convince the manufacturer that you are in fact the rightful owner, and they may be persuaded to sell you a replacement.
Edit: is it the Panasonic CQ-DF88 that you have the link to???