1) Snacks or otherwise salty goods that are purchased for a much lower price than they would ordinarily retail for.
2) Revenge that happened too quickly to be served cold, or taste sweet. It might have been done differently to how you wanted it, but it was still tasty and cost you much less time and effort than other methods. Salty bargain!!
1) Look at this half price gammon. Salty bargain!!
2) I was going to torture her for years with the idea that Imight tell her husband and eventually make her cave in and tell him herself. But then I just emailed him. Salty bargain.