Will a car of R 750 000 make you three times happier than a car of R 250 00? Is it three times as comfortable? Most people will agree that the answer invariably is "no".
Anyone can find an affordable vehicle and affordable camping equipment, with a bit of patience. A new vehicle is absolutely not a requirement and camping equipment are often bought and seldom/never used. The (mostly) unused equipment is therefore resold for a fraction of the price.
The cost of visas and passports is also not a concern, since South Africa has enough places to see for a lifetime of holidays. Since many locals are awed by holidaying in other countries, there are plenty unspoilt gems in our beautiful country.