Just came across the issue that e.g. Firefox caches the state of a select-box on a page reload.
Since the prices, displayed in my "Add to Cart" form, are attribute dependent. It's possible, that the displayed prices don't fit to the cached select-box state, after a page reload.
To prevent this confusing state, we should think about adding the HTML attribute
autocomplete="off" to the whole form by default.
Code to do so:
$form['#attributes']['autocomplete'] = 'off';