I usually stick between 2-4oz. On occasion, with my favorite (Tai Ping Hou Kui), I will purchase a half pound from a private supplier/garden in China, but he splits it up into two 4 oz. containers. I was lucky this last season becuase he sent me a whole pound and only charged me for half becuase it took so long to get in touch with him, but I have been trading some of it with others. On a general rule of thumb you want it to be as fresh as possible, unless we are talking Pu-Erh's, which in that case would add to the flavor and whole experience. I suppose if you had great/ideal storage you could get away with purchasing pound/half pound, but tea is kind of like food......you could go to a bulk grocery store and buy 10 loafs of bread for 20 bucks, or buy 2 at Food Lion for 5 bucks.......you might spend a little more, but what are you gonna do with the other 8 loafs of stale bread???Throw away food and cash in the long run. I am just rambling now, but you get my point! Hope this helps!
-Nick (Tai Ping)