Well as everyone has mentioned above BAT, craigs, ebay are good places. I actually found mine on EBay many years ago. When I was on the hunt I searched multiple places daily for a few years before I found mine. These cars are pretty rare & dont come up very often & when they do you have to be ready to buy. Two more places not mentioned above are the Honda S series club on Yahoo and few other forums.
After finding mine I ended up finding a few more and actually helped another member from here find himself one. I still have a few contacts and I know of a few more that are out there waiting to be brought back to life.
Within the past few years the prices have gone up A LOT. These cars are coming more to light & are getting the recognition they deserve. We can all thank Jay Leno for that and a few other people which is a good thing. More cars are being saved and history is being brought back to life.
Here is a little inspiration. viewtopic.php?f=3&t=8552