Applying ED2 unless you’re absolutely sure is a no-no. It really does make other students and parents upset to see this kind of post. My D, for instance, applied RD and is still waiting to hear back from BU. But, BU will let your D out of the ED2 contract if attending is not affordable for your family. Some schools are pretty flexible on this, I think. It happens.
And, no, I would not think it was “worth it” for my D to attend BU if there was a comparable, equally prestigious option available at 1/3 of the price.