This. I found a few bicycle co-op like things in Tokyo and Kyoto on my first visit in 2010 and good grief, not cheap! Renting a bike though wasn't bad. I'd consider shipping a bike. I built a Surly Traveler's Check for another trip this year, but I still have to manage the case, which has me considering getting a soft case because it will double as the bike bag that's required if you're using the Shinkansen or other trains.

Used clothing however, super cheap and in excellent condition if you're into that sort of thing (I am).