Some great points in this article.... though I didn't notice anyone mention the ability to relocate stations.

An orbital platform has mobility and can move outwards as new stations are built and/or launched (building from space would be ideal) - this type of system would keep the oldest stations the furthest from earth(/factory) and the newest ones with all the latest bells and whistles closest.  Furthermore a platform is easier to move out of the way of oncoming collisions.

A stationary base on the moon or other large body takes additional fuel to enter and clear it's gravitational orbit and seems to me would surpass the building costs over time. In addition, the base would constantly need upgrading as new technologies emerge.