It really depends on which part of Thousand Oaks you are looking to buy. There are parts of T.O. where homes can be found in the high $400,000s however, you have to be very, very careful and work with a sharp agent. Some of these homes were built long time ago on soft soil and the foundations of these homes are not that stable.
But, you can find nice decent homes in good neighborhood with good schools in mid to high $500,000s.