Custom theming

I suppose theme_uc_product_price() is actually deprecated, since it was replaced by uc_price() and it wasn't updated to use it.

Try using this code:

  $context = array(
    'location' => 'product-view', // You may want to customize this value to indicate that you are using a custom template. Your call.
    'class' => array(
      'product',
      'sell',
    ),
    'subject' => array(
      'node' => $node,
      'field' => 'sell_price',
    ),
  );

  print uc_price($node->sell_price, $context, array('label' => FALSE));

Now, I haven't seen that anyone has made a VAT module that uses the price handlers yet since it's still very new. You shouldn't actually see a difference in the price yet, unless you've got more code than I know about.

The price field handler should be running the value through uc_price() on its own already. I've tried to fake a node object, but it only has the values that are selected by the View. You'll have to figure out what your discounts need to know about the node, and add that data as fields. You can then exclude those fields from being displayed. Not everything will work this way (I'm particularly thinking of taxonomy terms) since they aren't attached to the node through node_load() and it has a different structure.

You can get the original value by calling uc_price() again with the same parameters, except changing the "revision" key of the $context. The full list of revisions is
- 'original' => Original price value,
- 'altered' => Original price passed through the alterer(s),
- 'formatted-original' => Original price passed through the formatter,
- 'formatted' => Altered price passed through the formatter,
- 'themed-original' => Formatted original price passed through the theme layer,
- 'themed' => Formatted altered price passed through the theme layer.

subscribing

So, I'm going back on what I said about theme_uc_product_price(). It's no longer deprecated, but it's signature has changed to look like

  function theme_uc_product_price($price, $context, $options = array());

These parameters are passed directly to uc_price(), so to suppress the label, you should add 'label' => FALSE to $options.

The reason for doing this was to allow the product view page to wrap the prices in block-level divs like it used to. theme_uc_price() only outputs spans which made the products look odd.

It was hinted at, but never discussed thoroughly to record the amount of each alteration to a price. That wouldn't be very hard to do, especially since it's up to the alterers to do that.

Tagging.

Yeah, this is done. And, in fact, there is a uc_vat module that changes the way prices are displayed.