I wrote about Koots and Starbuck's green tea a while back. My regular morning drink (when I indulge myself) is now usually a green tea latte. I really like the taste, and it seems to give you a more mellow lift than coffee. (At Starbucks I cut the sugar by asking for only one pump of Midori Melon syrup, instead of the three they usually put in).
I decided I'd try ordering some matcha powder online a few weeks ago, and looked around for a good retailer. I settled on Essencha more or less at random - I've never heard of them before, but their prices were decent and their website looked good.
I can heartily recommend them! Their service is incredibly fast and very personal. I got an email from them a few hours after placing my order (they noticed that I used essencha@domain as my email address - something I do with new online accounts to catch whether people sell or leak my info to spammers). They took the time to look at my personal website and said some nice things about my pictures. (On a side topic, I should really get my India, Nepal and Tibet pics back online properly - a lot are missing).
Anyway, after the nice email, I was already quite impressed with them. The tea arrived a few days later, nicely packed and with some free goodies thrown in: an extra 1oz of tea (kukicha) and a chashaku. The Matcha Sawa and Matcha Jade Bliss are excellent - I haven't tried the kukicha yet.