When I am looking for cheap and easy, I usually book through these guys:

http://www.japanhotel.net/

They have several offerings in and around Osaka. I'm using one of their places on my next trip to Japan because it is walking distance from Shin-Osaka station, has free wifi and breakfast and is under 7k yen/night. I'm getting in late, leaving early on the shinkansen and it works out great.

JR