Good luck!  I have a nice one of zero custom and 
I found it a year and a half ago & paid a pretty 
penny for it.  Cels of zero custom OR epyon that 
are nice (in my book meaning key cels or the mech 
alone with no other mechs in the image with it) 
are insanely hard to come by, hence super-
expensive.  

My hubby has an EXCELLENT epyon cel that cost him 
a bit more than the rest of our mech cels (with 
the exception of the zero custom cel) but it is a 
muli-layer key cel with its original matching 
background -- so there's the reason for the extra 
dough.

So, if you're willing to shell out more $$ than 
usual for a mech (i'm talking in the $150+ range) 
you might find one. 

Happy hunting ^_^

--zerospace