Forget Silicon Valley: It's gotten stupid expensive. The rest of the US, however, has not.
I lived in Spain, and moved to the middle of the US, to a city that is about the same size as Valencia: Here, A 4 bedroom house can be had for $200K. Groceries are often cheaper here. Cars are WAY cheaper here, barring a few EU luxury brands. My mother's electricity bill, in an apartment less than half the size of my house, is double mine, so the cost of living is in no way higher than in Spain.
The difference is that someone right out of school will make 60K. A completely average senior dev makes 100K. The last time I had local work I had a long term hourly contract, 40/week average, that paid $125 an hour, so 20K a month. Today I make more.
So in Spain you have a cost of living that is not really any better, far higher taxes, and pay that would be seen as pretty low for a recent college graduate. Every time I visit, and people ask me why I don't come back, I just go through the economics, and Spaniards quickly agree that I'd have to be insane to come back.