Good luck with the tank
I recently got into saltwater and have enjoyed it thouroughly. My tank is a 30 but I plan to move to a 90 in the near future. I figured if I can keep my 30 stable without problems, moving to the 90 will be easier.
You can get a 20gal setup going pretty quick with minimal expense. I started mine with simple equipment, I kept it simple and my tank is rock solid. Some might say the way I have it setup is wrong or that I am using the wrong equipment but it has worked and all is well.
I have 20lbs of live sand and 30lbs of live/base rock, my tank cycled and my fish are doing great. If you are new to saltwater, like I said keep it simple and see if you truly enjoy and can deal with the maintenance that comes with it. If you can keep that 20 running good, you can certainly keep a larger one going.
30 gallon FOWLR, BioWheel 150, 100watt heater, LED lights, Koralia circ pump, BioCube circ pump - Keep it simple
2 Maroon Clown fish, 1 dottyback, 1 hawkfish