bitslice:

it's around £80 to send something that is over 2Kg

It's always worth shopping around. I've got a quick quote from payperparcel.co.uk for 4kg to RSA for £58 + VAT = £70. There are other sites that will give quotes including interparcel.com, parcel2go.com and others.

As mentioned though, there may be taxes for the recipient to pay.

The big reliability concerns should come with anything going through the standard South African postal service. Amazon, for example, wont ship to South Africa unless you pay extra for a courier service. Personally I would look first for South African sites and second for a suitably reliable shipping option.

If you arrange for anything to be sent internationally, it is not impossible that the recipient could be asked to pay some tax and this could spoil the present. If the UK anything valued over £18 (or £36 for gifts) could be subject to VAT, duty and handling charges being added and this could amount to around 30% of the value. I don't know the rates/rules for RSA imports.