It all depends- if you want all brand new and top of the line than it can be super expensive. It also depends on your goal- if you want a huge sps
reef than it's gonna be a lot more than a medium size fowlr
and you can always turn it into a reef down the road.
For my current tank I went all used and DIY except for the lights and skimmer.
75 g tank from craigslist- $50 but is scratched up and I had to re-seal it with new silicone
DIY stand & hood- $100
Mag 7-$70 but have seen used for $25
Coralife skimmer $120
2 x Tao LEDs- $235
20g long (sump) $20
Acrylic for DIY overflows, glass for baffles- $25 scrap from hardware store
Plumbing supplies- $30
Live rock- $250 50 lbs or so at an avg of $5/lb (would buy from lfs
Base rock- free! Got at least 80lbs from uncle who had a reef years ago. In DT and sump.
Refractometer- $30 from eBay but started with hydrometer which are $5-10
Test kits- $50 for API SW
master and reef kit $30 for redsea mg
Powerheads- $100 for 1050 & 750 hydor koralias
Heaters- $40 150 w jäger eheim and a free 150 w I got from a friend not sure what brand
QT: 10g, basic little hob
filter, small heater all for $50 from Walmart.
I don't make water yet so I buy 15g SW
every 2 weeks (change 7 g per week) for $15 and 5 g rodi
per week for $1.50.
My next purchases/ upgrades will be rodi
unit from brs for $130 and eventually a better skimmer maybe reef octopus which is $350.
I buy $5-10 coral frags bc I like to watch them grow out and in case they die.
So it looks like my equipment was $1170
+ $10 per week for water
Livestock I've probably dropped $200-300 over the 2 years since I've started.
I'm sure I forgot a few odds and ends but that pretty much sums it up.