As others suggest, you need to plan ahead. They get big. So if you don't plan on being able to house them yourself, you need to figure out who can take them off your hands.
I tried to get one a LONG time ago. A LFS near where I work I real good about ordering stuff for me. I asked for a "small" one. Well, what came in was almost 2 feet long! It couldn't even turn without hitting front and back glass in a 125G. I had to bring it back. It was an awesome fish, and easy to feed.
About a month ago, I saw a really tiny one. About 5 inches long. I would've bought it, but my tanks have just taken a different direction since that first one.