I suggest there should be seperate menu/tab of international market in which resource are displayed with prize on it from high to lowest. 

In this civ can set prize and increase in deals with other civ will result in gain of prize at 5-10 turns and decrease in deal will cause drop of prize.

Due to this diplomacy will come:

If player drop prize very low can see a increase an increase of relations with some civ and decline of relation of civ competing in same area.

I suggest there should be some powers with civs:

Ban the traders from targeted civ for entering player territory but this is most aggressive.

Imposing tarrif on civ which will decrease trade between both.

Allied embargo: In this we can make alliance with many civs and can place embargo on targetted civ. These alliance are fragile and can end after solving of situation.

Trade Points: These show that currency used in the game world. 

It is achieved by increasing trade.

The more trade points will increase our  power of tarrif because of which in international market price will get increased.

seperated international trade system what you explain is already existed in AMPLITUDE's former games like EL or ES2.

roseofsharon wrote:

seperated international trade system what you explain is already existed in AMPLITUDE's former games like EL or ES2.

What you will like to add in it.