I really wouldn't know where to buy these cels, 
as I was lucky enough to be in Japan when the 
first one was released and, like I stated in an 
earlier post, the cel store let me buy their 
sample copy.  Each one cost me 30000 yen.  
Perhaps in a few weeks, they'll start surfacing 
on more cel sites like the first set.

W/ regard to marcus' post, I don't think the 
value of the repro cels in this case would be 
lower since the cel I have is licensed - as the 
package has a sticker w/ the license information 
as the other repro cels in the series.  I was 
told by the store employee that the unnumbered 
ones were only distributed to cel stores 
(approximately 20?), thus not available to the 
general public, making them more rare than the 
numbered ones.  Still wondering though...