You want Collette's in Bulawayo to do them. They take possession of the real ivory, make a flawless reverse casting with the serial numbers and dates even retained, then they hand paint them to perfectly match the patina of the real ivory. Runs about $600 as a wall hanger version, I think about $1000 on pedestals.
Best part, you can just walk them through the airport if you pick them up in Zim at a later date, rather than paying a fortune in shipping. (probably cheaper to go on a second safari than to pay international freight these days)