There's no single definitive answer to the average price of a car in 1925. The average price varied greatly depending on the make, model, and features of the vehicle. Also, data collection methods were less sophisticated then than they are today.
However, sources suggest the average price of a new car in the mid-1920s ranged from $600 to $1000. Keep in mind that this is in 1925 dollars, which would be significantly more in today's money.