well, something to show the colors better would be a simple 2 bulb t-5 fixture. it doesn't need to be much. one daylight and one actinic bulb should make the colors pop.
check out the current Nova Extreme HO Light Fixture - 2 x 39W - T5 - 10,000K/460nm - 36 in. for approximately 100 dollars.
now if you want corals, that's another story entirely. what corals do you speak of? mushrooms, xenia and such? then a nova extreme might be ok. if you are referring to lps, or perhaps even sps/clams/anemone, then you'll need to go a bit higher.