Aqua-Con The name says it all! Do a vendor search at Reef Central or The Reef Tank then ask yourself just how lucky you feel? There prices are very cheap to be sure but they have had a number of shipping issues, warenty issues, and very poor customer service when you do have a problem with a shipment! I wished I had known about these forums before I placed and order with them. The invert clean up crew arrived okay but the coral and fish shipment...half were dead when they got to a friend in Washington State, where I had them shipped before being shipped to me in Yokohama (something I have successful pulled off with Live Aquaria, GARF, Soutas, Clams Direct, Reeftopia and several others). Thier prices on Live Rock can easily be beat by almost any other company, even after adding the shipping cost 9 times out of 10. Thieves they are! Look at some of the pictures of thier live stock on thier website! Many were high-jacked from Live Aquaria and Clams Direct just to name a few. Some have even been stolen off personal websites that people have displayed thier tanks on.
IMHO...They are a trust worthlyless, company with few if any morales of any kind. I dont recommend them and I wouldnt use them no matter how cheap thier prices were, end of story. If you do decide to use them use at your own risk.
For corals, I recommend Reefer Madness, Soutas and Dr Mac & Sons. I am sure there are others I just dont have much experience with them.
Clean Up Crew, You would be hard pressed to beat Reeftopia! I use them exclusively about three times a year for orders. I even get a call from them when they are about to put something really choice on thier website so I can get the jump on the getting while its good!
Calms, Calms Direct sets the standard to be followed, just gotta be quick for the choicier picks when they restock before they are snapped up.
For rare and unusual colored corals, if you dont mind small frags and pretty proud prices, GARF can make for a good find too! I always buy GARF Grunge, Grunge Light, and mangroves from them everytime I set up another tank. I believe premium Aquatics has an item comparable to GARF Grunge for a fraction of a cost.
Just some other places to consider if you havent....