First of all, instantkamera, nice to see another green tea drinker, is there a tea forum or anything?
Luckily I'm too young to have ever been addicted to coffee/tea. However, I was addicted to coca-cola for quite a time which was horrible. I used to buy 1/2 cans every day, and my teeth have suffered for it (plus my pocket, 2x60px5=£6.00 a week at least). You may want to add up how much you spend on coffee, not sure if you go to starbucks or what.
It wasn't so much my teeth that made me stop, it was the fact that I had a caffiene addiction, and the fact that I didn't want to spend so much a month on a drink with such a high chemical count, when I can have water from the tap for next to nothing.
I then started drinking green tea, not brewing it correctly to start with, so thought it was horribly bitter. Started reading up on it and realised I was doing it wrong... oops. I think quitting something that's part of a routine is hard, but finding a substitute is what needs to be done, i'd take instantkamera's advice if I were you.
How many cups a day?