I was thinking the exact same thing.  In 
addition, if this is a commercial seller and you 
have a phone number, I would call him.  People 
seem to take a live voice a little more 
seriously, in person of course is better still, 
but you probably live far away.
It's also not such a bad idea to remind the 
person that his business may be in jepardy if he 
doesn't respond soon.  If he has any sense at all 
he won't want to risk future sales - I definitely 
avoid sellers I have heard bad things about on 
the forum or from friends if I feel there are 
good reasons not to deal with the person.