In japan there is no ebay, its all yahoo auctions. So from time to time ill troll through the track section of yahoo auctions.co.jp. I really think its an underutilized resource for japanese frames and parts.
Gipiemme Tecno R424 track specific rim. Got a 28 version of this on my ride.
mint 55 cm 3rensho
If you live somewhere other than japan, the sellers probably wont sell to you. Its recommended to use a 3rd party service . My friend did this when he bought his white samson, got it for like 900 shipped.
I did a quick google search and found this intermediary service. Dont know how legit they are, i know there are others too.