Depending on which part of the shop interface is used, buy/sell prices appear in the opposite category in the other interface.
"Traditional" interface sell prices become "trade network" buy orders, buy prices become sell orders; likewise "trade network" sell orders become "traditional" buy prices and vice versa.
- Initial conditions (ignore existing orders): no order for Yellow Paint: no price set for Yellow Paint:
 - Buy Yellow Paint at 10 cr.:
 - Trade network shows sell order at 10 cr.:
 - Order removed:
 - Add buy order for Yellow Paint at 10 cr.:
 - Shop now sells Yellow Paint at 10 cr.:
 






