Too many variables.
I can say this, though...
I've read this a lot lately: for setting up a saltwater tank (FOWL), budget roughly $50/gallon for setup costs.
Also, my own experience. I've got 46g and 10g tanks, both freshwater, tropical, community. After setup (including fish), my expenses are:
$3-$4 per month for food (combo of flakes and frozen food.
$1 per month for dechlor, roughly. Probably a little less.
Water costs are negligible. For me, at least. My bill hasn't gone up noticeably since I started my tanks, six months ago (of course, the total for water is only about $5.50).
Roughly $1.25/mo for electricity, lighting, I'd guess.
Couldn't tell you how much for heating. I have no idea how much power the heaters actually use. At a guess, I'd say maybe $2-3/month.
So, that's about $7-9 per month, or roughly $100/year for "maintenance". Not including fish, plants, and medication.