Self drive versus guide

We have a 24 day route planned from Cape Town through the Garden route to Shamwari, over to Drakensberg and then down to Santa Lucia. We then head to Kruger with a pit stop in Swaziland and the panoramic route back to J´burg for a couple of days. We have been quoted approx 14/15,000 euros just for the driver/guide not including entrance fees, lodgings etc. I understand that its an expensive option (driver´s time, lodgings etc.) but we feel a bit nervous about self driving such great distances.

Does anybody have a guide/driver that would be less expensive? Would self-driving be ok? We´re a couple with older kids (18, 16 and 12) and we have driven lots in NZ and Australia but this is our first visit to SA and to Africa in general.

Many thanks!!