Salt isn't hard. FOWLR
tanks are just like freshwater, really. You'll want to get yourself aggregate sand and porous rock, be it live, cured, macro, base...whatever. Follow one pound per gallon with both.
With reef tanks, we suggest using ro
water. You can easily get away with using distilled water, especially with a FO
Of course you'll need salt, any will do so whatever is cheapest. To go with this, skip over the hydrometer as they are inaccurate, and get yourself a cheap refractometer so you can keep your salinity accurate and stable.
Of course a heater.
You will need a small powerhead for water movement.