You don't necessarily get money. You have to be selected as a National Merit Scholar before you get money from the schools that do not participate in the college-sponsored program. National Merit Scholarship Corporation - NMSP
read the winner selection paragraph underneath that.
I think the top Ivys give 2500 to each Scholar. I'm not sure about the others but Princeton offered $2500 for the National Merit Scholarship, but I did qualify for financial aid. Try looking to see if you are eligible for corporate-sponsored ones because they often pay much more, i.e., Pfizer gives 12000 over 4 years, which is much better than the one-time installment of 2500 even though you do not get the distinction of "National Merit Scholar"