I'm conflating multiple variables, but the whole is reasonable. If SF would build enough apartments (starting 20 years ago!) it is reasonable to expect that you could rent there for not much more than Des Moines. Given that lack of space in SF - they are not making more land - owning a place will always be more expensive than renting, but high rise apartments amortize the land costs over a lot of people and so it need not be that much per person. Neighborhood is important too: if you are right next to the big jobs centers you should expect to pay more (in Des Moines downtown apartments run $2000 for a 2 bed room - they have just started building them though so I expect that price to come down in 10 years.)