Is this the tea you mentioned?
Oolong Tea (aka White Tea) is also good, it has a higher polyphenol content than Green tea.
www.beyond-a-century.com sells all kinds of bulk vitamin/herbal powders, super cheap! I highly recommend them. You can buy gelatin capsules and cap your own.
They sell a few Green Tea products, one 50% EGCG, for easy mixing in hot water (1 cup of it is equal to drinking 4 cups of plain Green tea). They also have a 98% EGCG product, but you have to cap it (it's not drinkable).
There's nothing like a nice cup of Green tea, it has an amino acid named L-Theanine which promotes relaxation (even though Green Tea also has caffiene).
They've even isolated L-theanine and sell it as a seperate supplement. It is popular in Japan, apparently they have gum and soft drinks spiked with L-theanine.
Is this the tea you mentioned?
No, Oolong is not white tea. Oolong is halfway between green tea and black tea. White tea is even less processed than green tea.