For what its worth.....
I went to South Africa in 2010. The total trip was 13 days and I was in country for 10 days. I can tell you that the cost of the trip and taking 5 nice plains game animals was less than (including the taxidermy work) $12500. I can't vouch for the number of exotics in Texas but I can tell you, a hunter will see more game in 4 hours of hunting in South Africa than you will see in a lifetime of hunting in the states.
As to the 'high fenced' concerns, many of the places in South Africa are also fenced. When you are hunting thousands of acres of land, you seldom (if ever get near the fences) and it isn't anything like 'shooting fish in a barrel'.
Based on some of the prices I have seen for exotic animal hunts in the states, I really doubt you will be saving any real money over an African hunt and you will miss the opportunity to experience the Southern Hemisphere, the millions of animals, the beautiful scenery, and a chance to get to know people from another nation.