$200 I think can be achieved if get freebies and 2nd hand items here from fellow reefers. A bit difficult though but possibilities are there. If need coaching, here got a lot of gurus.
I remembered when I just started, using existing 30x30x30cm tank come with lights, purchased live rocks, sand, filter media, salt, no skimmer, DIY cpu fan... all less than $200. But not include livestocks and corals.
Need to closely monitor water parameters though. A lot of top ups and regular water change needed. Slight deviation in parameters may cause harm to livestock.
Happy reefing and welcome to this poisonous hobby...