Cichlids are the cheapest when they are young, in my area anyway. It really depends on what your looking for. Would you like african cichlids, American cichlids, new world cichlids? Since you have such a large tank you can get the bigger fish or a bunch of the "smaller" fish. African cichlids come in a large array of colors. And are very fun to watch. I also have some American cichlids in a different tank (Africans and Americans don't mix we'll). I have a jack dempsey and a gold saum. You can look up different care needs for different cichlids and see what kind you want to end up with. I'm sure any way you go you'll love it!
