Green tea and cakes

Does anyone know of a local source for Matcha (green tea powder)? I need a small quanity for a special cake commission I'm creating next week?  I'd really rather have some of the proper good ingredient than making do.

FYI and Promotion: the green tea cake will be served at an art show reception, for senior artist april hannah llewellyn, at UAH. Details here: http://www.aprilhl.net/

Just a (How's This For Creativity?) list...
all done this year:
Sasha's Checkerboard Birthday Cake
Mardi Gras theme King Cake/Boob Cake
Valentine's Day Key Lime Cheesecakes
Bloody Heart Boob Cake
Dr. Seuss Green Eggs & Ham

this weekend:
Brenna's Anti-Birthday Strawberry/Goth Cake
Next week:
Art show reception cake, Kimono and Cranes theme