Joburg -Botwswana-Namibia-Joburg

I wonder if anyone can help with some suggestions. Next year, I want to make a trek to Botswana, then through to Namibia, and then back to SA. What would be the best route to take, where do you stay once there, how much petrol do you have to take, what permits do I need, what game reserves are best, and all done on a shoe string!! Or not,on a shoe string, but I don't want to take a loan!!
Thanks in advance, and sorry about all the questions!

Hi Ian and Sue,
Living where you do I presume that you will be driving a 4x4 on your proposed trip. If so, it opens up many additional possibilities, but a 4x4 is certainly not a necessity. The amount of time at your disposal is also a major factor in deciding upon the route. But here is a quick and dirty suggestion:
Johannesburg to Serowe (Botswana) via Martins Drift. Stay over at the Khama Rhino Sanctuary (chalets or camping)
Serowe to Rakops to Central Kalahari Game Reserve (4x4 necessary). Camp in the GR - pre booking necessary.
Rakops to Maun. Camp at Audi camp, do a mokoro or other trips into the delta, or a flight over the delta (expensive; value questionable).
Maun to Sepupa on the pan-handle. Stay at Drotskies a little further north. Do a full day trip down river, also a sundown trip.
Detour to the Tsodilo hills. Camp there for a night or two.
North into Namibia, camp at Popa Falls
Popa Falls to Rundu and on to Etosha (this is now very expensive - prebooking required). Arrange your time so that you can spend time during the nights watching game at the waterholes at Halali and at Okaukuejo.
Etosha to Twyfelfontein (Petrified Forest, magnificent San engravings). Camping available.
Twyfelfontein to Skeleton Coast and south to Henties Bay and Walvis Bay.
Walvis Bay to Sesrien (camping - prebook) for Sossusvlei and the dunes.
Sesriem to Duisib Castle (camping).
Duisib Castle via Helmeringshausen to Hobas (camping) for the Fish River Canyon)
Hobas via Keetmanshoop to the Quiver Tree Forest (accommodation).
Q Tree Forest via C17 and C15 to Mata Mata - a new border post has very recently been opened there. Spend a couple of days in the Kalahari Gemsbok Park.
South to Upington and Aughrabies falls (camping or chalets).
Aughrabies - Kimberley - Bloemfontein - Maseru - westward across Lesotho, down Sani Pass to Underberg.

Much refining of that route would be needed.
Enjoy.