On top of what Michael said, there is only to add that this myth that Ryokans must be expensive comes from the issue that Ryokans are normally not as space-effective as modern hotels - and therefore more expensive when it comes to downtown locations.

The maintenance costs for wooden build type of the room, the tatamis and the "live in your own home" style service level is not manageable for a 300-room sized Ryokan - next to the fact that a 15-floor building is not really what you would call traditional Japanese architecture. But if you want to pay the real estate costs (i.e. inheritance tax on property, etc) for a downtown location such as the famous Tawaraya inn in the middle of Kyoto, you will have a certain pressure to either be expensive or convert into a western style hotel where you have a much higher sqm-efficiency to justify the investment. The cheaper ones left in Tokyo can most probably survive because they are so rare and therefore ARE popular with tourists, have a high occupancy and are able to pay their bills.

Therefore, cheaper ryokans can be much more found in country-side locations and generally not so crowded places than downtown Tokyo or in the heart of a tourist destination. They can still offer the environment, but do not have the pressure to make room for a 70-floor high office tower.