If you have A B C D resources without reason in the game I would look over the design doc and remove the un-needed ones.

Every resource or number the player has to track should have a purpose. Like if you have a common resource like wood that can be found anywhere it is often the resource used for foundation units and upgrades.

A more scarce but still relatively common resource like metal, encourages expansion by being near enough to each other that building a base and a outpost between two spots makes the players control zone bigger.

Then a rare resource, like say gold, could be scattered over the map and be scarce; forcing players to explore and fight over it.

Last a supper rare resource like uranium can be used as a foundation for powers. So rare that even if a player collects it all they could se something like a nuke only 3-4 times. Making it both the most powerful and most wanted resource. Causing a perfect unbalance in the game

The actual worth of these resources can be calculated by monitoring the amount on a map and how much is used by the players.

No matter how well you plan this you can't really estimate the true worth of a resource. Race For The Galaxy is a good example. It has a Blue = 2 Brown = 3 Green= 4 and Yellow = 5 cards value. Even so most players agree that green is worth less than Blue or Brown.

In fact the only time green was ever any useful and very rarely was in the base game; the expansions turned it's true value into 1 card.