I'd say the first step would be to contact the 
seller and explain that the price you paid was 
based on your assumption that the cel was in 
reasonable condition for its age and series.  
Maybe they'll let you return it.

Failing that, or if you truly do love the cel even 
in its damaged condition, restoration sounds like 
a great option!  I'll be honest here -- I have 
three cels in my collection which have been 
restored by an artist friend who does excellent 
work. 

I also have two cels that look like they were laid 
flat on concrete and carefully rolled over by a 
truck... there's a weird bumpy texture to the 
acetate.  (Oddly enough, though, the paint is 
still intact and the image looks great.  O_o)

So, can you tell which five these are by the scans 
on my pages?  No?  Then why the heck should I list 
'em for you?  *grin*  If I was ever going to sell 
one of them, I'd explain either the damage or the 
restoration work which has been performed.

But I didn't buy these beauties for resale, I 
bought them for ME, and I still love 'em all.  
*huggles her damaged treasures, and doesn't care a 
whit if they're not perfect*  ^_^