Hmmm Let's see.....10 g SW setup: It depends on what type of setup you want. There are several to choose from. FO=fish only, FOWLR=fish only with live rock, then there are corals,inverts....so many to choose from.
Your basic FOWLR system:
Tank.(10 g Walmart,Petco etc.)...10 bucks
Hood/Light combo ....about 40 to 100 bucks or alot more if you want VHO bulbs
10 to 15 lbs of live rock.....about 80 to 140 bucks
Filter and/or skimmer....about 30 to whatever you are willing to spend.
Powerheads (2) .....about 60 to 80 bucks
Sand/Substrate....could be anywhere from 3 to 30 bucks..If you want live sand , it will be more.
Marine salt....about 20 bucks for a 50 gallon bag
Hydrometer....10 bucks
Heater......15 to 50 bucks
Test kits...about 30 bucks
And this is just to set it up. Then you have to buy the fish,cleanup crew and whatever, but the sky is the limit on that.
Have I forgotten anything?
Its not cheap. Any way, good luck. You do the math......
I know when I first setup mine.... it was a HUGE MONEY PIT..... I am still spending money on it!!!