Works fine for me
See example here. http://jsfiddle.net/blowsie/c6VAy/
Make sure your jquery is inside $(document).ready
function or similar.
Also you can improve your code by using jquery data
$('#amount').data('min','1000');
<div id="amount" data-min=""></div>
Update,
A working example of your full code (pretty much) here. http://jsfiddle.net/blowsie/c6VAy/3/