I know founders who've tried to do a relocation-financing startup. They failed to get traction and ended up running out of money. AFAIK, so did most of their competitors, as well as startups in the general "here are some nice other places to live" category you describe. (It was a pretty crowded space...you can bet that any market where there are Internet commenters saying "Why isn't there a startup doing X?" actually has several startups doing X.)

The root problem seems to be that the decision to move is basically emotional, and usually depends on life factors that no startup can influence. I'm here for two reasons: family and startup (my wife's family all lives around here, and I have a nascent startup where if it takes off, it'll be really handy to be close to investors). Among the other people I know who are thinking of leaving, or whom it doesn't really make economic sense to be here, what's keeping them is always similar things. They work for Google and there's no Google office near where the rest of their family lives. They grew up here and have sentimental attachment to the place. They really love the warm Mediterranean climate and can't imagine living in a place with snow or rain. When you dig into their lives, usually staying is actually the right choice despite the high expense, and it's more "Well, I wish I didn't have to put up with the cost of living and massive traffic snarls."