I think you should send him the cels. Afterall he 
kept up his end of the trade for the most part. 
Plus that's a pretty good deal you got. It 
doesn't matter what he might have done to others; 
it's just between you and him. Personally i just 
wouldn't feel right keeping the cel and not 
sending him his cels. In the past he ripped off a 
couple of people, but your doing the same thing 
to him( not sending the cels) wouldn't make you 
any better than him. By the way I am not 
suggesting that you are deliberately trying to 
rip him off.Hope that helps.