The Falcon Heavy is priced to lift cargo at less than $1,000 per pound, and can launch three times heavier payloads than the Shuttle. That would drop the nominal launch cost of the components for an ISS sized spacelab to under one billion dollars.

Space launch costs have already plummeted, and are poised to plummet even faster in the next decade. If the BFR is successful at full re-use (actually, it’s really if the BFS can be successfully reused often without costly refurbishing, as the BFR’s re-use is a straightforward repetition of the proven Falcon 9 approach), Elon’s crazy and bold claims of per-launch costs Of $5M are actually feasible.That would work out to something under $50 per pound, and the ISS components less than $50M to launch.

When full re-use occurs, it will be when launch costs start to converge near fuel costs, which are typically less than a half million dollars per flight.

if there's profit involved, then it will be feasible for other entities than gov'ts. For example, if a useful mineral that's hard to obtain is found on the moon (unlikely as it is...), mining and processing it into goods might be the impetus for such a change.