There have been tons of Caiman Lizard posts on Tumblr and they are becoming much more popular in the pet trade as well. These photos demonstrate the very unusual dentition of the lizards; they have molariform teeth. These teeth evolved to crush a very specialized prey: snails and other hard shelled aquatic creatures.
Anyone purchasing one of these guys needs to be able to provide them with live or fresh frozen snails and other shelled prey items. This can prove very expensive and sometimes hard to do. There are care sheets and reptile folk out there who will say you can convert them to cat food, rat pups, and other prey. Please, do not buy an animal unless you are willing to feed it what it eats in the wild or a very close substitution. Lizards fed dog/cat food and other improper diets often have hepatic lipidosis and other nutritional issues that cause shortened lifespans and health problems. If these guys were meant to be more generalized feeders their teeth would reflect that. Their entire GI systems have evolved to extract nutrients from snails and crustaceans.
In reptile exhibits at zoos these animals are fed snails, crayfish, crabs, and vitamin supplements. I promise that if there was a way to save money and feed something else zoos (especially the herp departments) would do it.
These are really amazing lizards and they can do pretty well in captivity but you must feed them what they are meant to eat. If you are willing and able to do that then more power to you, enjoy them.
(Top photo from Exoticpetvetblog.worpress.com, bottom by Udo M. Savalli)