That's an almost impossible question to answer.... I normally do the opposite, start with a budget (or sometimes I don't even have one) and find transport accordingly or use what I consider still to be somewhat value for money. But sometimes I chose convenience over cost :-).

But if you don't like to use public transportation and go everywhere by taxi you can run up quite a bill. It also depends a lot where your hotel is located. Although the better ones might arrange transportation on arrival at the station.

But I have never felt a big need to use a lot of taxi's in Tokyo, although it is sometimes nice before/after dinner or when you have been drinking.

Kyoto has some sights that are conveniently reached by taxi, busses can take a long time. A lot of the smaller places also have public transportation or you can book transportation to the more popular sites.

So it's mostly up to you how much you spend..... Ballpark with generous taxi use would be $200 a day for me. But that's way more than I spend, public transportation is cheap and I like to walk. I think I average more like $30-50 a day on a longer trip.