Botzzup is free. Unlimited chats. Unlimited bots. Unlimited websites. Unlimited agents. Unlimited visitors.
The only things you may pay, as you go only, is for additional Red/Green notifications (you get 100 of each at the registration for free), text-to-speech minutes and reviews requests.
But you can get those items for free if you go to the the settings menu (the portrait in the upper right corner) and click on Invite Users: add your friends emails: when they sign up: you and your friends will get mote free stuff each!