There are a bunch of them in LA. I set up an account with a couple saltwater suppliers but I no longer have saltwater tanks or sell fish.
On average 150 to 250 dollar min depending on the wholesaler. You have to have a couple pieces of paperwork generally, some dont care as long as you have money lol.
One that I was interested in is Southland Aquatics in Inglewood. I called them and asked their minumum but I didnt ask if they needed to see my paperwork. Some want a picture of your storefront (which I never had). I assume that those are the ones that sell online also and dont want the competition retail level.