RS,
When I went to Namibia in 2015 with Hunters Namibia Safaris, Marina suggested Nyati Wildlife Art CC in Windhoek, NB.
I got shoulder mounts of an eland, a waterbuck, and a black wildebeest (with flywhisk tail), plus a warthog tusk on a shield for $3750, including packaging costs and transfer costs.
Turnaround time was about 6 or 7 months.
If you want more information, feel free to PM me.
Don