HOWEVER … It costs a fair bit of money to get a saltwater aquarium up and running and maintaining it. Unless you’re going to locate to a warehouse and start a business selling coral, you will, like most who are in the hobby, use the profit of any coral sales to offset the expense of owning a saltwater aquarium and adding to your current fish or coral population.
Costs of running a saltwater tank include the tank itself, which can run into thousands of dollars, electricity, a reverse osmosis unit, filters, food etc! It certainly isn’t a cheap hobby. So swapping or reselling coral is a great way to offset these costs, if you’re not in it as a business. Have a look here how to post coral safely.