I would think that most fancel artists who accept 
commissions are unlikely to be trying to pass 
their work off as production art. However, there 
have been a few cases where commissions have been 
honestly fulfilled, and then the requester has 
turned around and tried to pass off the fan cel 
as real.

As far as backgrounds go, the hands-down best 
background artist is probably going to be 
Moonshine. I've never personally used Moonshine, 
but I've seen a lot of her work and am really 
impressed by it. ^_^ She does both cels and 
backgrounds. Her site hasn't been updated since 
May, though, and I'm not sure of her turnaround 
time.

As far as color-matching goes, I think Requiem's 
also your best bet... I remember the lovely Alita 
she did for someone on this board... but she's 
currently living on an island somewhere and I 
don't think she's taking requests at the moment, 
either. ^_^;;

So if your biggest concern is accuracy and color-
matching, those are the two people I'd think of 
asking first.

As far as the "Show Me" is concerned, these 
aren't the most detailed fancels I have, but 
they're my favorites of the moment and what are 
currently hanging on my walls. ^_^ Eriol (from 
CCS) and Ritsu (the Monkey from Fruits Basket).