There are several hotels outside the actual perimeter of the airport itself. A really crappy but cheap one are the Formula 1s complete with public service announcements in the hallways against child prostitution and AIDS. Hmmm...I've only stayed in the one in Nelspruit, but there is one just outside the airport. Super Cheap though. What direction are you heading in first?
Hopefully customs won't be too bad, however it was worse than usual our last two trips...world cup preparations. you will not recognize the airport at all! but be prepared to carry everything, when we got out last december, there were no luggage carts and we had four of the heaviest bags full of gifts for the holidays!