I don't think I have ever seen them have a sale.  
I think it even says on the site if you think the 
price is too high, too bad, the price is set.  
Yet I have seen them take down cels that haven't 
sold for a long time and upload them months 
later, I think sometimes at a lower price.  It is 
a bummer though, to get excited about an updated, 
and then find it's the same cels you didn't want 
6 months ago either.  :P  :)