Refactor purchasing batch views per master4

tailbone/templates/ordering/order_form.mako

@@ -288,5 +288,9 @@ ${h.end_form()}
   <td class="case-qty">${h.pretty_quantity(cost.case_size)} ${"LB" if cost.product.weighed else "EA"}</td>
   <td class="code">${cost.code or ''}</td>
   <td class="preferred">${'X' if cost.preference == 1 else ''}</td>
-  <td class="unit-cost">$${'{:0.2f}'.format(cost.unit_cost)}</td>
+  <td class="unit-cost">
+    % if cost.unit_cost is not None:
+        $${'{:0.2f}'.format(cost.unit_cost)}
+    % endif
+  </td>
 </%def>