Saltwaterfish.com is a good place to shop. Prices are very
reasonable. I love the free shipping. I purchased from them
once before with good result. My only complaint would be
everything has to be communicated by email. No phone number was
listed on the website.
If you want to buy fish, liveaquaria is another good place to do
business with. They have great guarantee and cheap shipping (only
25 bucks). As for corals, don't even get me started
. I love rainbowcorals.com, reefermadness.com; and I hear that reefscience.com is quite good as well.
A good place to find out about these things is the Vendor experience in Reefcentral