I keep on meaning to try Sakura onsen which is located near Sugamo station on the Yamanote line. There is a free shuttle bus and it is priced lower than the mega-onsens at 1296 yen for entry (bring your own towel or rent).

http://tokyocheapo.com/lifestyle/its...ll-very-clean/

LapLap posted it several years ago in the Tokyo onsen thread
http://www.flyertalk.com/forum/japan...kyo-onsen.html