But you forget, you don't need all of that from the get go. Including that much lr
understocked in terms of gallonage is not a problem. Instead of 45lb for a 30gal tank only 15 lb, and stocking at a 15gal level works and when the aquarist can afford more they add more. Many people run successful tanks with just a hob
filter, a sump or refugium is better but not the only way. Lights for fish can be very cheap as well and upgraded down the line all a fish needs it for is day/night cycle.
What is really needed. Tank, lights (don't have to be special), heater, some sort of mechanical filtration, substrate and rock (keep an eye on ebay and Craigslist, it can be really cheap and does not need to be live), and I would say access to rodi
water. (I would definitely agree best to have your own), salt and a test kit (not expensive and lasts a while.
Continued cost include, water, salt, electric. Does more need to be replaced, yes but not often, such as lights 9-12months, test kits, filters.
I have one 28gal tank, and run a qt when I get new stock, i still have my first test kit. As far as salt, by it by the bucket! 60 bucks for 175 gallons last nearly 6 months.
This is not a hobby only for the rich and snobby, almost anyone can do it, just at a slower pace. If you don't have an extra 40-50 bucks a month for improvements and general maintenance it might not be for you but it certainly doesn't have to be expensive either.