What is it that you're trying to buy exactly? This brand? http://www.hawdii.com.tw/

Anyway, if it's just some common local food it should be everywhere. Just walk into one of those supermarkets with a logo like the North Korean flag (called "Quanlian" but there's no English anywhere), and save yourself a lot of time: http://www.pxmart.com.tw/px/map.px