With the discovery that the eternal shade of lunar polar craters act as stores of water ice (no - not sno-cones) the doability of a moonbase has, definitely increased. Water provides, well, water plus - with solar generated electricity - hydrogen and oxygen. This means that with the resources available on the moon itself, life-support and vehicle fuel can be manufactured. This is without including the potential for mining metals and other usable solid compounds such as silicates for production of ceramics.
If we can truly 'set up shop' on the moon, with full cycle industry - from raw materials and native energy resources to finished building materials, life-support resources; combined with highly efficient use and re-use systems, we can not only imagine a self-sustaining moon base, but a space craft manufacturing center.
Since payloads of only some of the materials necessary for the construction of spacecraft would, therefore, have to be shipped out of the Earth's gravity well and the ships themselves would not have to achieve Terran escape velocity (and the incumbent structural strains involved), less material would be needed for the structure of the ships and less fuel would be needed to cross interplanetary distances.