Spinner, step, count value

Question

I've used jQuery-UI (1.9.2) and create some calculating functions. Bind them on select inputs, and you can see how it work here JSFiddle

I don't know how to make similar calculation function with "spinner". For example one step should be equal to (x)$;

<input type="spinner" class="spinner"
       value="0"
       max="10" 
       min="0" 
       data-fieldname="spinner_count" 
       data-days="13" 
       data-price="22">

For now i have this: http://jsfiddle.net/Strix/BQjPm/