Well the same web pages that say you can get a visa on arrival also say that there is a consulate in Nelspruit SA - which is on the way from Jo'burg to Maputo if traveling "surface". This being the southern end of the Kruger National Park, it might be a worthwhile "stopover"/

It seems the exMPM tickets are still in local currency as the USD prices (on ExpertFlyer) seem to change slightly over time.

Happy wandering

Fred