As I understand it, golf in Japan is pretty expensive due to the amount of (flat) land needed, something they are sorely lacking that can be used for other (more productive) things.
I was stationed in Japan once at a base that had a 9-hole course. I was told one of the best and fastest ways to make some Japanese friends was to invite some to play golf on the base. Mostly because (A) it would be cheaper and (B) they would actually get to play. I think I was told that courses in Japan could get backed up, so you would have to book time (far) in advance to guarantee play time. (This was in Kanagawa Prefecture. Yokohama was 30-minutes away by train, Tokyo about 90, so I could see that being the case.)
Anyway, pretty sure the pricing is just artistic license in play to make this somewhat believable given the cast. (Or that was off-season pricing or something along those lines. shrug)