Any tips?

I am thinking of driving from Jhb to Swakopmund, then fly back. The drive there should not be so bad, with an overnight halfway, but driving back is not something I would like to do. We are a party of 5 and it looks like return tickets (Air Namibia ?) would cost R15K. Half that one way. So would it be possible to do the down trip with a hired car for under R7K? Seems like the one way hired car trip will kill it, as there is a hefty charge for that? How does it work?

Avis is quoting over R7K, including the one way fee, but only 600km. EasyTerra quotes R1840 (161 Euro) , unlimited km's, but excluding the one way fee. Will phone tomorrow to get a quote on that. The car is a Honda Accord, suitable for 5 people?