‘How much to budget for a trip to Japan?’ is a difficult question to answer, especially given the wide variety of possible itineraries. According to the Lonely planet guidebook website, the very least one should budget is 7300 Yen ($60) per person, per day. This seems about right if you are using the Japan rail pass and staying in the cheapest hotels and hostels. However, it is possible to spend far less on many days during a trip to Japan.
Accommodation is perhaps the greatest expense; the cheapest beds in town usually cost around 3000 Yen. However, if you are prepared to camp or use the other cheaper alternatives given in the accommodation section, then this cost can be vastly reduced.
Traveling around can also be extremely expensive, but this cost can be reduced using the excellent rail and air passes. The cheapest of these, the Seshun 18 Kippu rail pass, reduces the cost further and is much cheaper than the Japan rail pass. Of course, hitchhiking will get you around for free.
In practice, we ended up using a wide variety of transport methods and accommodation options. We tried to use the cheapest ones as often as possible. This worked well, and while on some days we spent more than $60 dollars a day, on many days we spent as little as 2000 Yen ($15) dollars per day.