Ok, not knowing the specifics of your map setup, here's an (admitetly oversimplified) method of calculating elevation. Assuming (x,y) = (0,0) = center of the world: abs(x) + abs(y) = distance from center of the world.
Granting the center of the world some maximum benefit value, subtract (i.e. MAX_VAL - DIST_FROM_CENTER) to get "elevation". (If "elevation" doesn't float your boat, it could have to do with some sort of radioactive power source, or Mecca, or whatever other backstory best fits battlemines).
This "elevation" would be an attribute of each land square. It should be displayed on one or more maps (at least on War, possibly others.)
Possible uses: - Off set the land bonus (up or down) giving preference to being central. - "Lower tech" in the eyes of Ramul, making for easier trade when centrally located.
Note: MAX_VAL would have to increase as the number of players increased, but not at a very alarming rate.
Drawbacks: - It doesn't accurately calculate distance from the shore. - If n00bs are added on the shore, they'll be getting a penalty, however they start with 0 tech, so slightly inflated Ramul pricing wouldn't be too harsh.