A number of the people who sell cels on eBay are 
not major dealers like Taro and so would rather 
not deal with the hassles of international 
shipping because they are not trying to establish 
a consistent customer base. Some of these people 
need money fast for various reasons and the wait 
for the payment to arrive from a foreigner, along 
with the time needed to process it, could be a 
problem.

Another issue is shipping. Mailing a package to 
an international address is always more work than 
to one in the US because you have to fill out 
customs forms. (Not sure exactly about sending it 
to Canada or Mexico, but pretty sure for anywhere 
else, e.g., Great Britain.) And can you imagine 
the headache if the cel is lost in transit? It's 
bad enough trying to find a piece of lost mail 
within your own country's postal system, but good 
luck locating one that goes overseas. Even with 
tracking things get lost. :(

---Trebuchet