Listings can be sorted by custom fields. When you create a new field you can choose whether you want this field to appear in the ordering list in list pages. Multiple option fields like checkboxes and multiple select are not sortable fields.
In the link below you can see the Price field can be used for ordering:
http://demo2.reviewsforjoomla.com/directory/amazon-store/photo-printers/photo-printers_c12_m2/
