Dr. Paul Spudis is a serious Lunar veteran who has lead several robotic Lunar missions and is a most prominent Lunar geologist. Here's a plan of his to start out a Lunar colony with affordable small rovers, using the likely frozen volatiles at the poles as a resource for rocket fuel and human life support. More of his ideas.
The costs of settling the Moon consist to a large degree of the cost of transporting mass there from the Earth. By extracting basic resources, like rocket fuel and water/air for life support on the Moon, it can become much more affordable to build and support a settlement on that shore of the sky's sea, than the Apollo program. The Moon's axis is not tilted as much as that of the Earth, its poles have almost no seasons. The bottom of some craters are always in the shadow, as in since millions of years. The coldest places in the Solar System, it has been said. Some mountain ridges are almost always in sunlight. In the shadow there is water ice and other volatiles which are useful for producing rocket fuel and for life support. In the nearly constantly lit up places Solar panels could power a settlement. And they are located next to each other. A settlement there could enjoy both Solar and mined chemical power. And avoid the challenge of the half month long Lunar night that plagues all of the non-polar Moon and requires large power storages.
Since the Moon is nearby and geocentric, it is quickly reachable within a few days any time of the year. And robotic assets there can be remotely controlled from Earth with only a few seconds delay. So Dr. Spudis proposed concept is to begin with launching a series of small robotic missions to the Moon that provide a satellite communications network, stationary Solar power plants and, rather before that, rovers to examine the volatiles believed to exist in those nearly eternally shadowed craters and how they might be extracted since it is yet unknown in what mineralogical form those volatiles exist there. The Lunar Resource Prospector is a mission in this spirit, a rover that in 2020 will roll into those eternal and deeply cold shadows.
If fuel factories are established on the Lunar poles, visions like moonwards near the Lunar equator could be supplied by Lunar suborbital transports to complement the non-polar resources with extracted polar volatile resources. Very much cheaper than bringing it from Earth. Power and fuel made indigenous, only the engineered equipment (and the workers) needs to be imported from Earth as it wears out or becomes outdated.