Namibia is one of the less expensive options. It's a big country, so you need to budget 10 days to 3 weeks just to see the high points: Etosha, Swakopmund, Damaraland, Sossusvlei. You can go with a group or self-drive. While you can self drive, I wouldn't advise doing the longer trip without having a second car. In our more remote locations photographing the Himba people we were off-road up riverbeds, so we had two pick-up trucks for the 4 travelers plus I had 2 guides setting up camp. If you are only visiting Etosha and Sossusvlei Dunes, this can be inexpensive and easy self drive. I take groups of 4 to 8 to Namibia whereas in South Africa, Botswana, my group sizes vary from 6 to 18. That's how different Namibia is.
Airfare for a direct flight in May, Sept and Oct will be around $1200 from New York and be nearly $2000 in late June and July (high season). The trip itself can vary depending on lodges. A budget number would be to think $400/night/person all in, including vehicles, lodging, park fees, meals. However, it really varies depending on what you want to do. The park lodges are fairly inexpensive, whereas private reserve lodges can be anywhere from $200 to $600 per night per person. This was a 24 day trip and included 4 nights camping in remote regions to see desert lions, remote indigenous people as well as wildlife including tracking black rhino on foot and also shooting from helicopter over the dunes. btw, the helo will run you around $500/person for 2 hours flying time and takes 3 passengers at a time. I will admit that this trip also included A LOT OF DRIVING ON CORRUGATED, BUMPY GRAVEL ROADS. It was worth for this group as they wanted a full experience and all had been to Africa several times before. Info for past trips is on my web site, but don't think I'm suppose to 'sell' on the forum so I will leave it up to you to google Magnum Excursions and Buddy Eleazer. 
I will be headed back in 2020, but for 2019, my groups will be doing South Africa and Botswana in May and July and Kenya/Rwanda in September 2019.










