definitely elitereefs.com sign up for the mailing list every frag is ten bucks and his overnight shipping is always 21 bucks not to mention the crazy zoas he has!
have you ever looked at the zoas in liveaquarias divers den? nothing special, but they all have like 100+ polyps, and they are mad colorful. IMO best bang for your buck.
BlueZooAquatics has really good livestock (fish or corals). I like them because they will sell you more than a polyp or two.
VividAquariums has good customer service and healthy livestock. They do tend to be in the small frag business a lot and I prefer colonies but sometimes they have something very special.
I just tried a new site called Your Reef out of Roseville, CA. I bought some beautiful zoas from them at reasonable prices. But the zoas are not under the zoas section for some reason. You have to look in the soft coral section.
If you're looking for dendro's at a reasonable price, I like Roes Marine.
And last I have gotten some neat stuff from ExtremeCorals. He only list like 40 things but they are real nice and often different.