I am a Drupal n00b, but I have been tasked with converting a web site which contains some commerce like elements (contest entries) into Drupal. Basically, a possibly not-logged in visitor selects a number of categories, uploads the file they wish the contest to consider, may repeat that process for other file entries, and then proceeds to a page where they enter contact info, billing info, and CC info. The total number of selected categories, regardless of the number of entries, times the charge per entry, determines the total charge. There should be no adding to cart.