It's different for every chameleon. There is so much variation in a single species that is considered normal that we can't tell you definatively what is a 'good' weight. As long as it is healthy don't worry too much. Since you do have still growing animals it is even harder to say because they will still be growing and they grow at different rates.
Once they are adults, they should generally maintain their weight without gaining or loosing too much between weigh-ins as they aren't growing in size anymore.