[sundown]

Strangelov e: The mr carbon was on Italian ebay. I figured I'd be able to find Italian spearguns cheaper there. It eventually went for 50 more euros than the price I quoted, so unfortunately its gone now.
I have found Italian websites selling them new for around 400 euros, which is the cheapest I've seen them new.

Translated version of http://www.emporiodellapesca.it/index.php?cmd=prodotti&id_rep=2&id_categ=63

This is a translated version. Go to page 2. Don't know if thats too expensive but I hope its of some help and at least its a reference for any other C4 enthusiasts looking at this thread.