200g tank as a gift I wish I could be so lucky. Freshwater would be a lot cheaper. Saltwater is much more expensive and if your limited on funds it could take a long while to make things happen. Which can be a good thing because it takes a long while for the tank to become established anyway. Here is what I have for my 46g tank. Protein skimmer 200
80# of live rock 280 you would need about 250# or more
40#sugarfine sand 40 You would need over 100#
3 powerheads 80
3 heaters 60
Return pump/light 480
Testing kits 80
Trash cans for mixing 30
Coralife aqualight 220 for a 200gallon reef the light could cost about $1000
New stand to fit sump 100
Pile of stuff I didn't need 100
salt buckets $40 a piece for about 180gallons of mix 200gallon tank the salt cost adds up to your monthly expenses for sure.
Roughly about $2000.00 to get me started for my 46g tank. A 200g would be much more expensive for sand, rock and lighting unless you choose to do FOWLR
which the lighting wouldn't have to be as intense. other than that everything else would be similar depending on what you buy. I would definately price everything out for your tank and analyze if you can budget it over a 1 year period I would say go for it.