Construction System and Point Cost

I'm not sure if this has been addressed before, but the ECO points need
to
balance between ground and space forces.  IOW, when it comes time for
the
empire to spend resources for spaceships and invasion troops, the
relative
cost for a company of troops should be balanced with the cost of
frigate.

so my question is what are reasonable proportions between ground and
space
force purchases in a campaign setting?	I really cannot even venture a
guess
at the moment....

Dave