There is really only one steel drum band on island which is Provo Primary School's Senior Steel Drum Band. (my daughter plays in it). We've never seen another band at any other events. They will play weddings (and have been playing at some private parties on island this month), but it depends if it's during school breaks as many will be off island during those times. You can contact the principal of the school (email@example.com) if you want to find out if it's possible for your date and the costs. I don't know what they charge, but it goes towards the maintenance of the drums which is really expensive so they try to fundraise for it. Here they are playing Wipeout at the fools regatta this year
(they do know slower romantic numbers as well, we should have some new video up after this weekend when they perform at the Friends of the arts christmas concert)
A number of brides here have commented on DJ's here, you may want to do a search for DJ and Turks and Caicos or music and Turks and Caicos, I remember quite a few threads have been here on the subject and brides have given reports after their weddings.
Hope that helps