It wasn't talking about the tank cost, specifically, it was referring to all said and done--stocked and all (and on a new setup). I didn't believe it, to be honest, but with my 34g Solana, I'm near $2K... well over $50/gallon. (Including lights, chemicals, accessories, rock, sand, salt, livestock, blah, blah, blah.) That's fantastic that it is a lot of re-use! That'll definitely mitigate it.
I pointed out the potential cost because I didn't fully grok how expensive the hobby is until I saw all the bits and pieces adding up... rather quickly, mind you. So fast, in fact, that I stopped itemizing all my purchases. At this point, I would rather not know.