You can find some homes in Encino, Lake Balboa, Tarzana, and Van Nuys in the 400K range, they may not be 3+2, more will be 2+1, but there will be some. You don't say where you work and what other things might be important to you, so those are some good choices off the top of my head. You can search on my website, or call me if you like, so that I can get a better sense of what the nicest neighborhoods for you might be.
David Krecker, BSBA, SRA, MRA
Centuryside Real Estate Inc.
Broker/Owner/State License Appraiser
Serving the areas of Orange County, Los Angeles County, San Bernardino, and Riverside.
There are lots of options, depending upon your needs.
Agoura is a lot different than the valley, and the SFV is pretty big, so you might need to narrow down your search a little.
If you'd like some assistance I have an associate that work in the valley. You can contact me via my Trulia profile.
I grew up in Toluca Lake. I know some agents will say there areas are best but where the values are highest and truly are great neighborhoods to live in I would put Toluca Lake, Sherman Oaks, Encino, Woodland Hills, Studio City, Valley Village and Burbank. If you would consider a condo (those areas you may not find a condo in with 3 bedroom, Other options would be Valley Glen and Lake Balboa. If it's a home your looking for and not a condo then North Hollywood and West Van Nuys might be doable options.
The Reavis Group at Keller Williams