These show up on Yahoo Japan fairly regularly.  
There are two on YJP right now (although they're 
a tad pricey):

http://page3.auctions.yahoo.co.jp/jp/auction/c2645
9360

http://page4.auctions.yahoo.co.jp/jp/auction/d2282
5946

If you haven't done this yet, check with a number 
of the "big dealers".  One way to do this is to 
visit this URL:

http://www.cels.org/db/keep-track.pl?cat:1

And then visit all the dealer sites that have 
updated in the last couple of months.  There's 
got to be a few of these cels out there;  I see 
them all the time...