How to display ng-model input value as currency in angular?

I'm having in html

<input type="text" ng-model="price" >

<h2>{{ price | currency}}</h2>

In controller

$scope.price = 10;   
Which displays   **$10** in h1 if i change the value in price model input.

I want the text box input to be in currency ($10 in input box as value). How to achieve this?