Visas are required by all except South Sudan nationals.
Visa prices vary from US$160 for US passport holders to US$50 for African passport holders.
Prices and rules vary between embassies. At some embassies you may need an invitation. Issue time of visas may take a few days or weeks depending on the embassy.
Diplomatic and official passport holders can obtain a visa for free. Visas on arrival at the airport are not available unless you have made prior arrangements.
We have had reports, from tourists, that visas arrival can be obtained for US$100 at the borders with Kenya and Uganda.
South Sudan Embassy Washington DC