The version I have of Technidol is sold in tiny bottles here in Holland. I think one little bottle makes 600 ml. I guess that as long as you keep the little bottles tightly sealed, they will keep for a very long time.
I tried Rodinal once for Technical Pan film, but I did not like it as much as Technidol. As 'Konical' said, it is expensive but certainly well worth the cost.
Hopefully Kodak will keep making Tech Pan film, and Technidol, because it is a lovely film for details in nature.