All (yes, all) the top schools are need-blind, meaning they don't look at your financial situation when deciding whether to accept you. A few of them (Stanford, Harvard I think) are offering completely free tuition if your parents make less than $100k. For other situations, you typically would get around 75% of your tuition free even if your parents make over $100k a year.
The difference in first year average salary for an MIT grad vs. a state school grad is enough to make up that difference.