I don't particularly like the phrase bargaining, but I think there are ways to put a little icing on the cake.
I think it is 100% fair and normal to ask an outfitter what the cost would be for x number of days for x animals even if they have a price list with no packages. Imo, there should be quite a bit of wiggle room for RSA and Namibia. Let them answer and if you don't like it, move on. I wouldn't start haggling over prices: "your kudu is $2000, would you take 1500" just makes you a dumbass imo.
Little things that incur minimal cost can help seal the deal. Throw in a baboon or a night hunt. Ensuring a particular side trip is available.
A big area for negotiation is with non-hunting guests and family. Often observers are like $150 a day. For what? Does your wife eat $150 worth of food??? Maybe you want to bring your kids. Again, I wouldn't start haggling against their stated prices, but throw it out there: "I really like your 10 day package. My wife would like to come along and she's low maintenance. What can you do as a package upgrade for her to come?"