I think it's reasonable. FWIW, many private schools here require a term's fees at the same kind of time of year to reserve a place, which will be thousands of pounds, and that's well-established schools. TBAH, one of my worries would be whether their $400 is *enough* to make the information about who's signing up reliable (i.e., is it enough to deter all but those who almost-definitely intend to send their child?). If I were you I'd have a Plan B for the case that you sign up, so do at least 4 other people, so you're told it's all on and you give up your Montessori place, but then on the first day of the new term not enough people actually turn up to make paying the teacher's salary viable. The deposits will not go anywhere much to help in that scenario.
