http://www.ruhn-chan.com.tw/
Although it is a Taiwanese drink, I was surprised they had ENGLISH on their website.
The drink I tried was the Bitter Melon tea! The sweetness was light and not syrupy at all.
It had the full strength of bitterness a natrual bitter melon would have.
Other drinks of this brand that I have tried:
Ruhn Chan Herbal Tea