Aikibuken of Obata Sensei is definitely worth a look, try
www.shinkendo.com or
www.aiki-buken.com for more info.
There are some Hakko Ryu teachers in the LA area as well. Although a derivative of Aikijujutsu (Daito Ryu), it's quite effective (read painful). One Hakko Ryu teacher, actually Hakko Denshin Ryu, is Gil Adams in Pasadena. There are also a couple of teachers of mainline Hakko Ryu teaching in the LA area as well although they are pretty low profile.
There is also Yanagi Shidare Ryu Aikijujutsu of Soke Don Angier, the last I heard he was accepting two new students. I've also been told there are a couple of other teachers of Daito Ryu in LA, but have yet been able to contact them.
There are a couple of Shorinji Kempo schools in LA as well, which is an offshoot of Aikijujutsu (Daito Ryu).
Lastly, there are some excellent Aikido teachers in LA. If you are looking for something with substance (aside from Aikibuken) I would highly recommend Robert Bryner Sensei (Nishio style Aikido) in Santa Monica, and Jacques Payet Sensei (of Yoshinkan) in the Valley, Patrick Auge Sensei (Yoseikan Budo) in Rolling Hills area and a few others...
Feel free to email me if you have any questions.
KG