If you don't have the tank I recommend NOT getting them. You could actually become attached to them and feel bad when you have to get rid of them. Those big cichlids can be like dogs, especially when they recognize you when you come into the room and say "hi".
Also, if you buy them and dump them on someone else later wouldn't you feel bad if their lifestyle isn't as nice as it should be. What if water quality sucks and they get sick and die. People should not buy fish they cannot take care of. If you do it just encourages people to sell those MonsterFish even though most people cannot house them properly.
There are many other reasons, but hope you get the idea.