As others have said you would need to create the backend first which would be far more complicated than the angular.js frontend, Node.js would be the best bet if you wanted to avoid PHP and already know javascript. I remember seeing a couple of open source Javascript faucets that you could probably audit and convert to a Node.js backend with some work.
As far as a database is concerned being that you are handeling currency my suggestion for a nosql db would be Redis or CouchDB, Avoid MongoDB for something like this.
Thinking about going with Redis. Thanks for the help, really appreciate it! To you, and to everyone.