JSDF Uniforms are very rare and usually very expensive (outside japan that is expect to pay upwards of $300 for a set)
The last reatailer that I know of that had them was
www.worldcamo.com however i'm not sure if he has any left.
Other then that ocassionally they do pop up on Ebay (Make sure to check the other Ebay sites outside of the .com)
Also if you can find/know a japanese writer check Yahoo! auctions japan
http://auctions.yahoo.co.jp/jp/ I've seen kit on there as well from time to time and you might be able to arrange something.