Merrigo Kidz

It has some very useful features like the instant pop-up on pressing 'buy it now', and the app has customization of what you want to communicate at every state of the logging in process. It pretty much solves all our problems as we were struggling with other apps earlier. Their support has also been very prompt in resolving few issues we had.

It's one of the best apps out there for creating highly customized pages. I'm highly satisfied with the site that I have been able to build, and the support staff has always been very prompt and helpful in solving any situation.