The cost of salt in classical times has been rather severely exaggerated: salt was fairly expensive by modern standards, but nowhere near as expensive as precious metals, and a generous quantity of salt for culinary uses was readily affordable on a common laborer's wages. The cost of salt was largely driven by both mining and seawater evaporation being labor intensive and time-consuming.

u/arandomnameinserted goes into some detail on this related thread on salt production and why it was expensive. I also have a couple comments of my own in the thread going into more detail on how expensive salt actually was in classical times. https://www.reddit.com/r/AskHistorians/comments/gm17y3/at_what_point_in_history_did_salt_go_from_an/