Method 1
1, Buy grain for 30 gold
2, Make flour for 5 gold
3, Sell flour for 38 gold
Gives a total of +3 gold for every flour you sell.

Method 2
1, Buy sapphire for 75 gold
2, Sell sapphire for 78 gold
Gives a total of +3 gold for every sapphire you sell.

Method 3
1, Buy wood for 17 gold
2, Make coal for 10 gold
3, Sell coal for 32 gold
Gives a total of +5 gold for every coal you sell.

Method 4
1, Buy bitter herbs for 25 gold
2, Buy 2 poisonous mushroom for 4 gold
3, Make poison for 5 gold
4, Sell poison for 50 gold
Gives a total of +16 gold for every poison you sell.

Method 5
1, Buy crab for 6 gold (or catch them for free)
2, Buy empty bowl 8 gold
3, Buy 2 eggs for 3 gold
4, Make crab soup for free
5, Give the soup to the man outside the pub in town and get 30 gold
Gives a total of +10 gold for every poison you give. (+16 gold if you use free crab)

https://cs2bus.com/sharedfiles/filedetails/?id=2556026593
https://cs2bus.com/steamstore/app/259550/Hero_of_the_Kingdom/
https://cs2bus.com/sharedfiles/filedetails/?id=2556354174
https://cs2bus.com/steamstore/app/346560/Hero_of_the_Kingdom_II/
https://cs2bus.com/sharedfiles/filedetails/?id=2556355130
https://cs2bus.com/steamstore/app/772430/Hero_of_the_Kingdom_III/
https://cs2bus.com/sharedfiles/filedetails/?id=2556356201
https://cs2bus.com/steamstore/app/1249130/Hero_of_the_Kingdom_The_Lost_Tales_1/