Knockout.js Custom Money Binding

EDIT: I think I've found a better solution. Click here to see the post on creating a money observable.

As I've been digging deeper into knockout.js, I had a need to simplify some things. I needed to have my view model hold float values but display it as a formatted money value. Time to write my own custom binding for knockout.

I'm a bit mixed about this. On one hand, it was dead simple to get the behavior I needed. On the other, the semantics don't match up. The built in bindings are things like text and value. That is, you are mating an object to the text or value property of a DOM element. DOM elements don't have a 'money' property, which makes this approach feel wrong.

There it is and I'm not confident that I'm using the tool appropriately. What do you think?