With regard to costs, you really can spend what you want on a safari, but remember it is very easy to spend a lot of money if you aren't careful.
You can easily do a hunt in South Africa or Namibia for $10,000, and less if you try. Daily rates in both countries are very reasonable, you can easily find a good hunt with daily rates around $350-400. The safair operators make their money not by charging a daily rate, but through the trophy fees they charge. If you want to keep your trophy fees relatively low, you'll shoot game like impala, warthog, springbok, blesbok, burchells zebra, bushbuck, kudu, gemsbuck and wildebeest. The animals that cost a lot in trophy fee are generally eland, nuyala, sable, roan, lechwe and especially dangerous game. Trophy fees for lion, leopard, elephant and buffalo are much higher than for plains game.
With the wide variety of countries, safari operators and animals you can choose from, you can find anything you want in Africa, ranging from a low of about $7,000 up to well over $100,000 for a single safari. If you have the money to spend, a 30 day safari in Tanzania with one of the top operators like Tanzania Game Trackers or Robin Hurt Safaris and a full bag including elephant from Masailand can easily go way over $100,000. If you don't have big money to spend, you can do a quality shorter hunt of 7-10 days for under $10,000.
My last hunt was with Spear Safaris in South Africa's Limpopo province, and we shot a kudu, nyala, impala and warthog in 5 days, on the end of a family vacation. Spear was excellent and I'd recommend them without hesitation. On the other end, I've done long tent camp safaris in Zimbabwe and Botswana and those are fantastic too, but you can go on 3-5 trips to South Africa or Namibia for what one of those hunts cost today.
I highly recommend any of you considering Africa to check out Spear Safaris. They do it right.