18 months, 36 months, bah still rare as my wife's steak.
Actually it looks like a couple months after the one 18 months ago, there was an unlisted (in title) darxide up inside a lot of megadrive games on e-bay, found this thread:
http://www.sega-16.com/forum/archive/index.php/t-12809.html
It might have been 5 years before that to get to the next recent wave of darxides. I can't find any other references inbetwen 2003 and 2010 for darxide appearing on e-bay.
Oh wait, looks like one in 2005, one in 2007
Ok so we got 2002, 2003, 2005, 2007, 2010 (x2), 2011 (x2)
Probably around 1 every 18 months on average. Some might be on uk only e-bay. If they don't offer international shipping they don't show up on my searches.
I still think it's a terrible game.