Location to Call the function theme_uc_price($variables)
Since it's a theme function, based on DrupalContrib theme_uc_price it's called about 12 times within the Ubercart Suite.

As an example from one of the functions that calls the theme function which is uc_object_attributes_form.

theme('uc_price', array('price' =&gt; $option-&gt;price))


That's how Drupal uses theme functions.