It's okay to say so. I on the other hand think its better if they accept you first and then you tell them to try and work out some sort of plan with them about financing your education before you reserve your spot in the class. I think they would be a lot more willing to work with you if they've already accepted you. Others in this board have said to use the fact that you're undocumented as being something you've overcome to get you where you are. Whatever works for you.