I have been out of the tea game for a while, but here are a few personal favorites that I come back to:

Adagio Tea's Scottish Breakfast ($0.11/g)

Vahdam Tea's Daily Assam ($0.06/g, but you have to buy 340g)

Yunnan Craft's Zhong Guo Hong ($0.09/g)

Yunnan Sourcing's Black Gold Bi Luo Chun ($0.12/g)