You have several options to express the same thing: 1.) In Tokyo, if you bought these Ingredients I have been using for my breakfasts, it would be 3 times more expensive than that in the U.S.. 2.) In Tokyo, if you bought these Ingredients i have been using for my breakfasts, it would cost three times more than that in the U.S. 3.) In Tokyo, my breakfast ingredients are 3 times more expensive than in the U.S./ In Tokyo, the food for my breakfast is 3 times more expensive than in the U.S. 4.) In Tokyo, my breakfast ingredients/ the food for my breakfast costs me 3 times more than in the U.S. They are all fine and I think used equally frequently, so it is up to you which you prefer.

The ingredients I use for breakfast cost three times more in Tokyo than in the U.S. You can say the continuous “I have been using…” but the verb “use” here implies the present simple form, repeated action. Also, you can say "my breakfast" but it's not necessary unless the context with other sentences makes it sound like you make breakfast for others, like "I take care of my mother, too. Her meals are inexpensive but the ingredients I use for my breakfast cost three times more in Tokyo than in the U.S." I hope this helps.

All of the above answers are good but I will comment that I don't like the use of the word "ingredients" in this context. I find that non-native speakers (including my mother) often use the word "ingredients" in this context but my sense is that most native speakers use the word more in terms of things that are used in packaged and canned foods or sometimes in recipes. A more natural way to express the idea (IMHO) would be "The things that I usually have for breakfast cost three times more in Tokyo than (they do) in the U.S." If you want to emphasize that these are things you buy and bring home rather than things you buy at a restaurant, you might say "The things I buy to make breakfast at home cost three times more in Tokyo than (they do) in the U.S." Note that the words "they do" are optional. People will know what you mean if you omit them.