He's probably too busy dealing with his regular business, so
he doesn't bother to check the emails.  Selling cels is 
only his hobby/part time job.  Last time I saw him, he said
he is scared to open the email box because it's always
flooded with emails, he has no time to answer all these
inquiries.  Plus he's not a technical person.  The best way
to deal with him is to meet him directly at the convention,
like next week's Anime Expo.