All prices for farming goods are dynamic and calculated globaly between the different servers. That means the price for iron bars on server 1 is the same as on server 2. The price calculation is a complex process and depends on the number of items sold and synergy effects between the items.
The current prices of legal goods can be checked via the "market app" for the smarphone or via the userpanel. Prices of illegal goods can only be seen if the "black market" app is installed on your smartphone.