It depends significantly on the type of tank. If it's FOWLR you can go even cheaper than the par 38s, as you don't even technically NEED light for that type of tank. If you're keeping softies, LPS, SPS, or a mixture of two or all three types, the lighting requirements are different. So without knowing what corals you plan on keeping, I can't fully answer your question. Also keep in mind, especially in this hobby, cheap oftentimes doesn't mean good. I could steer you towards some Marineland fixtures (for example) that are relatively dirt cheap but IME won't keep corals worth a darn.
I would definitely be interested in keeping corals. I know that sps need more light, however can you tell me the light requirements for sps, as well as the kind of lighting I would need for just softies and lps?