For a fish only tank you need salt, good water, maybe some basic test kits, lights, thermometer, hydrometer (measure specific gravity -> salinity), a protein skimmer, and probably some kind of cannister filter.
You could go with live rock instead of the cannister filter, but you may want to run carbon in a cannister filter anyway. A 45 pound box of live rock (LR) would modify your fish only (FO) tank into a FO with live rock (FOWLR). Live rock would get your cycle started and can make for a beautiful and natural display. It may also provide food for your fish (amphipods, copepods, various worms, etc.).
The lights would just be basic normal output flourescents. Put some actinic bulbs in there to show off the fishs' colors.