Let's just say that we could explore the Moon by paying what we are paying now for the ISS. Would the average citizen of the US and Russia prefer that to continuing the ISS? I think so. Especially if European and Russian astronaut were involved, I think world interest would skyrocket. They could de-orbit ISS in pieces via shuttle and mothball the rest until required.

The US would commit to building the shuttle-c (which really should be called STS-C) and an updated Apollo CSM, modified to carry 4 astronauts on return and with enough fuel to boost both the ascent stage and CSM out of lunar orbit so that the ascent stage could act as additional living space both coming and going. The Europeans could develop the ascent stage and the Russians the descent stage and commit to launching it separately to lunar orbit on a Proton. Total mass of this LM would be just under 3 times the original, using the original descent engine as the ascent engine. Plan on about three missions to test things out. An alternative would be to do three man missions with a Soyuz, but I am not sure whether they are still lunar-return capable, and you would need to add a large engine to do the lunar orbital maneuvers anyway.

First landing misson would have the Russians place the descent stage in lunar orbit. The CSM and SSME powered TLI stage go up on the STS-C. Not having to lift the LM or LM shroud should keep this payload within weight limits. The ascent stage and crew would launch in the shuttle. The three person crew would undock from the orbiter and dock with the CSM. Then off to lunar orbit to mate with the waiting descent stage. Land at the Apollo 12 or 14 site to prove to the world that it really happened (site of Apollo 11 will become a world preserve later). Command module would be crewed on this mission but later could be uncrewed, offsetting the life support used by the fourth crewmember enroute. First person out would be the Russian. Later missions would have teams of two on alternate shifts, thus maximizing the use of lunar stay time. Then home with a classic pacific splashdown and parades in Moscow and New York. Isn't THAT what people want?