> there is no reason to expect a modern day lunar mission to cost the same relatively
By some rough math, the cost of the Artemis program as a fraction of national budget is on the order of 1/10 that of Apollo in its day (comparing entire program costs to national budgets in representative years). So no, I'm not sure anyone would expect (or accept) that, and indeed it does not seem to be the case. It would be even cheaper if Congress had not mandated that SLS be built from repurposed STS parts (and later that Artemis fly on SLS), and if Congress and the executive branch had generally maintained a realistic and consistent vision for the program since work on it began (arguably with Constellation in the 2000s).
By some rough math, the cost of the Artemis program as a fraction of national budget is on the order of 1/10 that of Apollo in its day (comparing entire program costs to national budgets in representative years). So no, I'm not sure anyone would expect (or accept) that, and indeed it does not seem to be the case. It would be even cheaper if Congress had not mandated that SLS be built from repurposed STS parts (and later that Artemis fly on SLS), and if Congress and the executive branch had generally maintained a realistic and consistent vision for the program since work on it began (arguably with Constellation in the 2000s).