I have also used liveaquaria.com and saltwaterfish.com.
Saltwaterfish.com often has deals where you get free shipping if you but a certain item (normally in the $50 price range - the list varies) and ships free regardless at $200. Their corals and inverts a pretty good, but their guarantee is a pain IMO
. You may receive a refund if you report a DOA within 5 hours of delivery. Beyond that it's credit only. (15 day guarantee) You have to uplaod a photo of any dead animals to their site.
Liveaquaria ships free at $225. Their guarantee is great. Just a phone call and they issue a refund. I think their fish are a little better than saltwaterfish.com, but their inverts aren't as nice. (14 day guarantee) For lesser amounts, you have to be careful that you don't order from variuous facilities and double down on the shipping cost. (Their WYSIWYG and captive grown corals ship from Wisconsin and everything else is from California I think.) Once you meet the free shipping amount, it all ships free though. they also have freshwater fish and plants.
Both sites have frequent sales.