I can only say in U.S. dollars.
I found that staying in a Ryokan was cheaper than a hotel (about $47.00 U.S.) back in 2001. I slept on a futon and was comfortable enough. I didn't miss having a Western-style bed.
You can find reasonable food prices at fast food places and elsewhere.
The only pricey items were the airfare ($550 through Priceline. com) and the JR Railpass (roughly $250). I went for a week and took $1,500.00 with me and came home with just under half that (and I didn't penny-pinch either).