Have you asked to see if they even still have it? They may still have some of it even though they do not have it listed on their site, I would ask at least.
http://forums2.gardenweb.com/f... This thread has someone in it trading seeds from "Century House" so if you contacted them maybe they would sell or trade with you.
http://www.birchwoodfarmsnh.co... here it is for sale, but I have no knowledge of the seller at all, just found this on a search. I would call them and speak to them in person at least and pay with a money order or paypal, unless someone on here can verify their legitimacy. It says on the site they are a member of AHS, I would verify that.
That's all I found about it.