Ed, he mentions about buying in bigger sizes...
Matcha a little beyond prime can be used as a blender or an ingredient in cooking.
I mix matcha with kukicha and even mediocre sencha with really great results. Matcha can turn blah sencha into something special. Because matcha is full of static electricity (so I have read somewhere) it clings like crazy to leaf and stem teas
I cook a lot with matcha and can always use more.
So, where as a past prime matcha may taste a little off on its own, it can be redeemed.