Thanks for the post about Airsoftshop, Nil8r, but here's the reply I got from them back a few weeks ago:
"Hello! Sorry this mechbox is out of stock now
thx
Airsoftshop.com"
SilentDragon...I've gotten the same response from WGC, UNC, Den, etc., etc., etc. Finding one actually available for a reasonable cost just doesn't look possible. Maybe look for a busted up AK and canabalize it? JT in Tucson says they expect to have metal ver III boxes made by SRC available in a month or so for about $100. We'll see what happens. Right now, anyone getting a Matrix and expecting to easily upgrade it is in for a surprise as far as I can tell. BTW, I agree, why isn't this gun made to be upgraded any more than other guns? Externals are fine; how can a mechbox changeout not be possible? Sounds like you already have the gun, so you're stuck just like me. If we knew then what we know now, we'd think Vince's offer was something to really think about. Good luck.