Value of luxuries

[Kimiimaro]

It happened several times in history. Some material became wanted, and the nation that had most of it became fabulously rich. For example, Brazil and rubber.

But let's get to the point. Imagine that you play as Brazil and you create a great jungle empire, and in this jungle empire, you have lots of cocoa plantations. Let's say that you have some six cocoa luxuries. And suddenly, a message would pop up and it would say that cocoa has became a wanted culinary delicacy. That would mean two things. First, it would give your cocoa plantations some type of bonus - bonus amenities or gold, for example. Second, the AI would pay much more to get this luxury.

After some time, the "wanted culinary delicacy" effect will fade and some other luxury will become wanted - let's say that marble has became a wanted construction material that gives more production. You don't have any, but Germany has a monopoly on it. You were trading with Germany to get marble for extra amenities in past. Your last trade agreement expired during the time of "wanted construction material" effect and you return to restore it, but you'll find out that Germany won't give it up for the same prize and it would demand something more, like more GPT.

 

[Boris Gudenuf]

There are some goods, natural or manufactured, that have had an 'Outsized' desirability throughout history.
Gold has always been desired, both as a pure luxury and 'prestige' good - every king needed gold objects around to show off - and as a necessary base for coinage/trade, and in modern ("Information Era") times as a component for connectors in solid-state electronics. While the reasons varied, it has Always had Prime Value as a trade good.
Silver was second only to Gold as an early Luxury, but even more important than Gold for Coins - gold coins are just too valuable to be handy in daily transactions, so in virtually every Civilization that had metal coins, silver coins were the mass that circulated - and greased the transaction process in markets, trade, etc. Some of the most enduring Wealth Generators were silver mines: Laurion in Greece, that financed the Athenian fleet, Joachimthal in Europe, that produced such a large percentage of Europe's circulating coinage it gave its name to the Thaler/Dollar, Potosi in Spanish South America, from which Spain exported tons of silver to China, who traded massive amounts of silk, porcelain and other Luxuries for the metal required to fuel its own internal market trade.

Another great source of Outrageous Desirability is, of course, in Dependancy Goods - addictive trade goods like Liquor, Tea, Coffee, Opium, and Tobacco. Once the people of a civilization get a taste for them, they will trade/pay just about anything to keep getting the good. Even better, and especially with goods that can be Highly Modified by technique and technology - like hard liquors and wines made in particular ways or from crops that grow only in certain specific climates - you can charge extra for Types of Dependancy Goods, even if they are just variations of something available somewhere else: like Canadian and Scotch whiskeys, French wines, Columbian Coffee, etc.

Finally, there are the 'Strategic' goods, which includes not only the game's definition but also goods that are used internally to make Life Better in the civilization.
True Strategic Goods would be, of course, Oil, Iron, Coal and their like - required to make units
But to the population, fine wool and leather for clothing (especially in a High-Latitude climate!) silk and cotton, Gemstones of all kinds, copper for 'primitive' metal tools and household goods, Manufactured Amenities like Automobiles, Consumer Electronics, Mass Entertainment, or decorated pottery (if you don't know how to make it yourself - and this definitely includes Porcelain) - these are all 'Strategic' also, in that people will not happily do without them once they've had access to them, or know that access Can Be Had.

One thing that should be included in 'cycles of Desire' for goods in the game is the fact that eventually, every single good either gets Replaced or has its Use changed.
Gold and silver no longer circulate as coins - paper money and now electronic transfers are making any 'solid' money obsolete. BUT they still have value in Consumer Electronics
Ivory as a luxury, Leather as a common item of clothing are either illegal or becoming too expensive - and both have been replaced by manufactured materials.
Iron, Coal, and Oil are all being replaced as the basis for manufacturing or as fuel/energy sources. The period of World War Two was probably the least time that the Steel Manufacturing Capacity of a country was any indication of its potential for manufacturing military hardware.

So, by all means. lets see some variation in the 'value' of Trade Goods in the game, but rather than have it change according to random 'whim of the market' base the changes on specific demands by your population or economy for which you have to provide a Good, or a Substitute, so have your Civ do without and take a hit in Growth, Happiness, Amenity, or some other In-Game measure.