Hello friend, I waited a lot for this contest, but this time I am somewhat confused in the use of your example as input I hope it is valid.
Buying
Name of Place: Busy City
Goods purchased: Filing Cabinets
Number purchased: 200
Amount spent on goods: $20,000
Selling
Name of Place: Establish Town
200 × 100 = 20,000. Seems valid to me.