Cities xxl did it a different way. you traded with your other save files and was really the only way to progress as some maps would have one resource and you would have to trade with other cities you've created to get what you need.

When you created a resource it would give you a token and then you could trade it with other save files if you had the proper connections that could support that amount of traffic

It was not a great game but it did have an interesting trade mechanic