Be aware that all dive operators in the gilis and on lombok have gotten together to fix prices. They will tell you its the government that has set the price, but it was admitted to us that thats a boldfaced lie. Just choose the operator closest to your hotel and save yourself some hassle.
I used reefseekers on gili air, they were great! Very careful divemasters, good with the environment. If you dive you must dive off trawangan; any lombok or gili operator can take you there, it is incredible.
Sad to report that Baruna dive of bali and lombok has very shoddy equipment and careless divemasters; I had one who dragged his gauges on the reef and manhandled the sealife. Give them a pass.