My understand was that Africa was cheaper than both exotic Texas hunts and Alaska hunts but taylor brings up a good point about the time factor.
As for the hunts themselves...... They run the gambit, even on the same ranches. Basically they will do whatever you want. Even the ones up here are plenty big for fair chase hunting while still being able to control the quality of their herds. It's hunting hands down. But I recall a story from a guide I was hunting with about a handicap fellow who wanted to shoot a zebra or two. They called around a found a couple from a drive thru zoo or something of the nature that was closing down, had em shipped in, turn em loose and went hunting a day or two later. He said that critters never strayed far from their release point and were like shooting fish in a barrel. All that seemed very pointless, only redeeming part was that the shooter was handicap. Cost was thru the roof though, talkin 10's of 1000's.