I went in June asd dove with Resort Sports ltd. They are located at Beach Club Colony. I think they charged about $300 for five days' diving. They were friendly and personable, willing to adjust locations and profiles based opon diver experience and skill, after getting to know us, the divemasters allowed us a lot more freedom for those who wanted it.
I felt very comfortable and safe with these guys. Diving there is easy and fun, it's hard to get into trouble or lost, as most of the dives are shallow,there is little current and good visibility.
Make sure you go to Sting Ray City, the most fun dive ever!
I also dove twice with Red Sail sports, they charged more and their boat was a huge, cattleboat type operation. But they helpful, and provided a good service, but I was on a boat with 20 other divers, it just seemed impersonal.
Enjoy your trip.