I think saying "I've discussed it with my parents, and I am prepared to take on the expense" is a good response, because, IMO, chapters like to hear that your parents know and support your decision to rush/pledge. If you just say "Ok" or "I've got it covered", it doesn't give the impression that you have thought about it in advance. OTOH, you want to avoid the sense that you are not taking any responsibility for it.