Radions appear to have caught your fancy, but like Coralgurl says, there are plenty of less costly LED options out there that will grow your coral nicely, especially for a 20 gal long tank. Kien's idea for a couple of Kessils sounds like a good match.
Haha I know. I don't know why but I seems to be biased towards radions and kesil. They just look so cool
__________________
You wouldn't want to see my tank. I don't use fancy equipment and I am a noob