Just about everyone carries clematis. Prices vary quite a bit. This year I have ordered clematis mail order. One of the nurseries I have ordered from came highly recommended by several clematis collectors and the pricing and shipping is not bad. I have not gotten the order yet but she carries the collection you mention and they seem like they are still in stock. Debbie does have a note on her homepage that she is busy doing shows at the moment and is taking longer than usual to email back. She was very helpful to me.

Here is a link that might be useful: Silver Star Vinery

i bought a beautiful red clematis plant (staked and already climbing) at popes gardens (popesgardens.com)...great stuff there!

I heard about Pope's. I am going there this weekend.