Basically, run the Net Price Calculator for the college. If the number it spits out is unaffordable, don;t apply, because FA won’t magically appear. If the NPC says that you will be paying full freight, then while you can get out of the ED agreement in January, it would be disingenuous of you to do so. But if you think you can string along the ED school while you compare FA offers from RD schools with the idea of trying to back out of ED in May, that would not go over well.