Saileur - I used Havin's, right next to Island Waterworld, he has a site at Havin's Marine
and I can recommend him for good work. While doing my boat, a 43DS anchored next to me also wanted a mount made and, despite holidays and travels, he got both done quickly. I asked for a particularly overdimensioned one and think I paid around $1000. See D400 Wind Generator
for some pictures.
Boatman61 - I never met the South African Gent, but did meet French guy with an electrics and mechanical shop about 50m inside the French bridge on the port side (no dock
, you have to tie up and climb up the outside) but he does great work and is also very, very accomodating and friendly.