If you look on the classified section of this site (and other sites) you can probably get a used 48" pc light for about the cost of a single coral ($40-50). That's my suggestion.
Now there are things you could buy, but typically cost close to as much as a used pc light, which is why I mentioned that first. You could get a sun coral, tube anemone, feather dusters (many kinds out there), non-photosynthetic gorgonians, and non-photosynthetic sponges. You may even be able to find some tunicates or sea squirts. Flame scallops are colorful and non-photosynthetic as well.
Most, if not all of these require manual feeding of various things. Also, most of them are at least moderately difficult to keep. I suggest researching any you might purchase individually.
I still recommend saving a little and just getting a cheap PC light because then you can really get quite a lot of things.