Hi,
We can demo many of our previous ExtJS projects via team viewer/Skype, including applications that have more than a million active users. Alternatively, we can send you a pdf that contains the screenshots of some of the screens.
Me and my wife have more than 8 years of hands on experience of working on ExtJS in one of the largest software companies in the world. We both are Oracle certified developers.
We now freelance full time. If you want this urgently, we also have some ready made applications that we can tweak to match your requirements.
Thanks and Regards,
Gaurav Jain