How much does it cost to go to California?
It depends where you are starting from and your mode of transport.
As one example:
The cost of driving from New Jersey (NJ) to California (CA) at a distance of 2856 miles, 25mph, with a gas price of $3.551 and a total gas consumption of 114.24 gallons is:
$405.67 one-way or $811.33 round trip.
This webpage tool allows you to insert your own starting point, cost of gas per gallon in your area, and your car's average gas consumption.
You would need to add in your costs for hotel/motel per night, and cost of food. Make sure to include extra time for road construction and stops. Driving straight through takes 43 hours, 32 minutes...but you need to add in time for rest stops and overnight hotel stays. Most people can only drive 8 to 15 hours non-stop or with alternating drivers--any longer driving at one time risks accidents.
You could also investigate taking a bus, train, or flying.