You can usually find it at any natural/organic food store. I use the Bragg brand.If you are going to use it, you should use the apple cider vinegar with mother in it. Haven't seen it in the store but I ordered a huge bottle for about $8. Most people will need to put it in water or juice to stomach it and you only need a tbsp or two.
On the topic, I like green tea and I drink it because of that. Don't know about the health effects but I don't drink it on a regular basis either. I have started taking green extract pills so we will see what happens.
You guys should watch your intake, though, because green tea reduces the absorption of iron from food, which can lead to anemia, so you may need to up your iron if you're drinking it on a consistent basis.