This is a short tutorial on using Price and Contact fields as custom fields and using it only on several categories.
First of all, please create custom fields with name 'price' and type input box.
This fields will be labelled on fields list.
After this, please go to DJ-Classifieds global configuration and tab 'Views' change parameter "Use 'Price' " to 'Custom field.'
Next, assign this custom field to categories which you want to publish. Then this field Price will be published as a custom field.
You can do the same trick with Contact extra field.