I just got a spare transponder key made up for my MY99 WRX as I was only given one when I bought the car (the person I bought it off had lost the other key).

I got my new spare made up in under an hour by Cobbler Plus in Joondalup Mall. The new key locks and unlocks the doors and starts the car. It cost me $189.00

They are one of the kiosks in the main atrium area of the mall.