Reddit mentions of Vita Life Brand Matcha Green Tea Powder, 10.58oz.

The best way to consume theanine is drinking green tea, as theanine is found most abundantly in the tea plant. The strongest green tea is matcha. Matcha is a finely powdered form of green tea. The powder is mixed into hot water and in this way the tea leaf itself is consumed. Matcha has many health benefits, of which theanine is merely one. Theanine is valuable to us because it binds with caffeine, and while our brains have many receptors of caffeine, which allow us to experience a caffeine rush (and subsequent crash), the brain has relatively few receptors for theanine. As a result, the theanine-caffeine bond can only be broken as quickly as the theanine can be processed, which results in much of the caffeine of the tea being sequestered by the theanine until it can be processed. Humans feel this as an 4 hour elevation of mood and concentration, with no crash following this period. More matcha, longer period of alertness.

In addition to being a theanine and caffeine powerhouse, one cup of matcha can have as much antioxidant EGCG as over 130 cups of traditionally steeped green tea.

I drink matcha regularly and enjoy it mixed with hot water and a splash of milk/honey, or mixed without water into hot milk and honey. Health information can be found here. High-quality matcha is extremely expensive, but I purchase low-quality in buk from amazon.

A few notes:

• Amazon sells high volumes for pretty cheap, but this is not Matcha. It is still powdered green tea, but it is a chinese blend. Matcha is Japanese in the same way that Champagne comes from Italy France (fuck).
  
• Matcha lasts a long time. Don't be followed by the 1-2oz tins. You use a dinky spoonful per cup.
  
• Mix it with a whisk. Add a little water at first, whisk until lumps are gone, then add more water as you prefer

http://www.amazon.com/Matcha-Green-Tea-Powder-10/dp/B001F10XUU/

I got this one and it is great for making lattes.

This one seems safe, I think?
http://www.amazon.com/Matcha-Green-Tea-Powder-10/dp/B001F10XUU/ref=sr_1_1?ie=UTF8&qid=1342760466&sr=8-1&keywords=matcha

Hah, you helped me make up my mind; I'm probably going to see if I can find a big container of powdered green tea.

I was looking around on Amazon last night and found this -

http://www.amazon.com/Matcha-Green-Tea-Powder-10/dp/B001F10XUU/

10oz for $20, a great deal over $10 for 1.5oz, right? It is actually a different product, but if I am to use it in cooking, it will taste functionally the same, but a tiny bit more bitter. The grade of green tea that I would feel comfortable measuring 2 heaping tbsp of would be this not ceremonial-grade maccha but "Hunmatsu-RyokuCha" powder.

I want to use a lot more, because I LOVE the flavor of green tea. I am also an old Starbucks green tea frappuccino junkie. :)