Airport shuttle is probably the cheapest, most reliable and safest. See http://www.airportshuttle.co.za/container_rates.asp?content=jhb for rates - generally Zone 2 for Sandton.
This might be more cost effective if there are multiple passengers, as you're paying for the car.
Ask them to confirm the name of the driver in the reservation, so that you can check ID at the airport.
Follow safe travelling advice as found on the worldnomads.com site - don't carry too much cash, have copies of your documentation saved somewhere on webmail, be cautious about where you travel at night, go in groups, etc
Have a good trip over 10 years agoAnswered by None None via Travellr.com