Dodgy Dave trades
Trade the indicated item after Dodgy Dave opens his special shop to get the indicated item:
500 gold: Trade a Special Medicine
1,200 gold: Trade a Reinforced Boomerang
6,000 gold: Trade Robe of Serenity
Bandit Axe: Trade Ring of Immunity
Big Boss Shield: Trade Crimson Robe
Happy Hat: Trade Sandstorm Spear