Add warning if no pricing data available

InvenTree/part/templates/part/part_pricing.html

@@ -36,6 +36,13 @@ Calculate pricing information for {{ part }}.
     {% endif %}
 </table>
 
+{% if buy_price or bom_price %}
+{% else %}
+<div class='alert alert-danger alert-block'>
+    No pricing information is available for this part.
+</div>
+{% endif %}
+
 <hr>
 
 {% endblock %}