You can get the WAT902H on eBay from time to time. It's almost as good. CR Kennedy are also very helpful for lenses, but you will have a very hard time to find a good Computar these days.
This is also a good guide:
http://sonotaco.com/soft/NSOG/equip.html
and the english forum too
http://sonotaco.jp/forum/viewforum.php?f=17
James