Another option for Florida Aquacultured rock is Gulf-View.com. I bought 30lbs from them a few months ago and was very satisfied.
you should first decide what type of rock,(fijji, Happai, Tonga, Fla. Aquacultured, etc.), you want and then research the retailers that sell the rock you want.
You also should decide what shipping method, air freight or delivered to your door, best suits your needs. Different MO retailers use different shipping methods for their rock.