I know
OPS Gear has camo paint (link provided) and I know they do their own camo work on guns. But I'm not sure if they will do it on a used gun, couldn't hurt to ask though via email.
Or you could get some two-color fades in Powder Coat from
www.cbsforless.com. Actually, now that I think about it, this guy that goes by "kingtime" has a site
www.kingtime.tk and he does alot of custom work with auto paint, I'm sure you and him could ponder about getting a Camo Paintjob.
I recently came across
this site too.
Good Luck.