For us, matcha is a strictly Japanese tea, synonymous with an ancient tea culture that dates back to the 12th century. Green tea powder brands that cost significantly less are probably not true Japanese matcha.
While tea-powdering is believed to have originated in China, the farming techniques for matcha were refined and perfected over several centuries in Japan. Preparing Japanese matcha is an intricate process which has been part of Japanese culture for centuries. In Japan, tea leaves are grown in the shade to preserve its green colour, and dried quickly to prevent them from long exposure with oxygen, which can dull the earthy flavour.
Chinese "matcha" only roughly follows these farming techniques. Chinese tea leaves are not generally grown in the shade, and are pan fried to stop oxidation. As a result, Chinese "matcha" does not froth as much and its texture is more sandy.
Chinese teas have also come under fire for their potential toxicity. In 2013, the environmental organisation Greenpeace randomly tested 18 Chinese green tea samples, and found that 12 of them contained banned pesticides.
The soil in Japan, specifically Uji, has different characteristics that have an impact on the taste and quality profile of the tea.
The process of growing and harvesting the tea is what makes Japanese matcha. So it is worth paying more to reap matcha's full health benefits, flavour, history and quality.