An added gotcha...
A lunar base means spending 14 days in lunar darkness. That means either lots of solar voltaics with regenerative fuel cells or nuclear power. Last time I heard, the Prometheus nuclear reactor was rated at 60 kilowatts. That's no where near enough power for a lunar base. The R&D for a multi-megawatt nuclear reactor is going to cost mucho dinero.
Gary
p.s. If we're only doing Flags and Footprints then we won't need the expensive nuke.