Market board price = how tradeable the town thinks it is
Your bag
Bag value 0
A true story first
Growtopia's money lost 99.7% of its value. The game kept printing it. I grew up trading in that economy.
Lowest seller prices per Diamond Lock in Indonesia: blog listings 2015–2018, itemku 2019–2026 (archive.org snapshots).
40 traders barter salt, fish, rice, cloth and wood. Nobody, not even me, can create goods or crown a currency. Every town keeps its goods differently, so the rulebook alone won't tell you which one becomes money. Read the market, guess before everyone else, stock up, and get out before the rains.