Items to consider when planning your safari to South Africa:
Kruger Park prices do not vary a lot during the year but prices related to your safari do.
Decide what time of the year you wish to visit - avoid busy times to improve your game viewing opportunities.
Airfares vary a lot so look for specials. Do some research to see which flights suit & which routes are less expensive. Use major Airports in South Africa like OR Tambo, Cape Town, Port Elizabeth, Durban where prices are cheaper because there is volume.
Monitor the Forex rate to see when the ZAR is weak against foreign currencies which is a good time to book & pay.
Choose a Kruger Park Operator who includes the transfer Johannesburg to Kruger Park & return.
Focus on the purpose of a safari which is game viewing - luxury accommodation is not a priority because you only sleep in the room then during the day you are out in the Park. Save your money for more upmarket accommodation in Cape Town or the Garden Route
Small group tours give you more personal interaction with the guide so you get more value from your safari - look for an Operator with good Reviews and ask if you have the same guide each day.
Check on the payment policy & methods of payment. Online credit cards these days are usually secure & not as expensive as bank transfers. Certain cards like Amex may offer perks such as Travel Insurance or less commission on international transactions.
Talk to your friends & family - share a safari which is fun & most Operators give discount for 4 or more persons.