Look at The Cooper Union for the Advancement of Science and Art. It's also in NYC and is VERY selective. It's a very small school and, up until this year, it was tuition-free. This year's freshman class is the 1st to have to pay tuition, but the tuition is still low as compared (maybe around $20,000/year). It might be too small for many kids, but it's a great school and right in Manhattan.