Store bought green tea
There are some really good buys available in Chinese supermarkets. There's a brand called "Asian Taste" that is organic and has Pi Lo Chun and New Spring Tea for under $2 a box. There's another brand called "Tradition" that has several teas among which is one labeled "Fresh Green Tea". This looks like sencha but is not vegetal tasting but sweet and only costs $3.49 for 2 oz. Both of these brands I've mentioned come individually foil wrapped and will last a good while.