The tour is free, but yeah, I had to pay transportation for myself and the guide (who I arranged online after some googling). The actual site is fairly far from central Tokyo, so it's about a 20-30 dollar train fare.
The guide himself was free, a nice older gentleman who used to be some sort of government liason. He insisted on taking a taxi for the 2 miles from the train station to the tour though, which was pricey. But I didn't have much of a choice (despite a whole face-saving false choice he offered of walking vs taxi that was deeply emblematic of a certain strain of Japanese cultural weirdness).
He offered to walk or take a taxi, but when I said I was fine with walking he just kept repeating the same the question with increasing emphasis until I agreed to the taxi.
The guide himself was free, a nice older gentleman who used to be some sort of government liason. He insisted on taking a taxi for the 2 miles from the train station to the tour though, which was pricey. But I didn't have much of a choice (despite a whole face-saving false choice he offered of walking vs taxi that was deeply emblematic of a certain strain of Japanese cultural weirdness).