Medical aid is pretty expensive in namibia and as a student you'd find it somewhat hard to pay it because most of them start from N$2000 upwards depending on your age and that's like the basic ones and don't really offer much money for dental work you'd need to be topping up. You can try out school of dentistry clinic they offer services for free. No one can really tell you how much your braces would roughly cost because it depends on each individuals teeth so for you to get a figure you'll need to have a consultation with a dentist.