Well, you can always ask the seller if they 
realize that the cel was from the wrong series 
mentioned. I have seen that happen with Kodomo no 
Omacha and Marmalade Boy in Cel Dealer/store 
sites. Mainly just one particular site and no 
matter how many times I tell them that the cel 
they have is not from that series they never seem 
to change it.

As for coming down on pricing I think I have been 
able to do that once maybe twice. But they were 
both from collectors. It all depends on who it 
is, how you word your request, why and of course 
the sellers disposition. 

Good Luck!