The Blue Book (available at the Bookstore, banks etc.) has the estimated prices of used cars. Look at it before you negotiate a price, and get the car checked by a mechanic before buying it. Avoid getting it checked at Accutune or Quality-Tune, even though they are the only ones open on weekends; they're a complete waste of money.
Before registering your car, you will need to get a smog certificate for your vehicle. This can be obtained by taking your car to a service station or auto dealer displaying the smog check sign.
It is illegal in California to drive a car without liability insurance. You cannot get insurance without a California Driver's License. If you think you may get a car in the future, you should get a California Driver's License as soon as possible because the insurance rates vary with the length of time that the license has been held. Insurance is expensive---compare prices. Many companies give ``good student'' discounts and junk like that. Bring copies of overseas car insurance policies; with luck you can get them accepted as evidence of ``experience'' and be offered lower premiums. And most importantly, refer to Bechtel Center's Guide for foreign students, which has excellent info on getting a licence and insurance, and buying cars.
It is a good idea to get towing insurance, which costs only a few dollars per year. If you are a member of AAA, this service is included. Even otherwise, it is advisable to become a member of AAA. The first year's fee is $44.00, and dues for each subsequent year are $32.00. The services include free maps and tour books, unlocking the car when the keys are locked in, etc.