thats a very hard question to answer as many variables would factor into that type of setup. the main question to start with would be what type of fish are you looking to keep? as with most things, some are much hardier than others and water quality doesnt have as much of an adverse effect: a quality skimmer would certainly be at top of equipment list though
You probably still need everything you need for reef except for fancy lighting, minor element supplementation, and only need to test for the basics (nitrate, ammonia, pH, nitrite).