I am trying to build an online registration form for an institute I intern at that is running a training programme with multiple courses and hundreds of applicants. I've done registration forms with Google Docs Forms before, but the tricky spot this time round is that I'm trying to put a registration cap on each of the courses.

Every person needs to register for one course in every timeslot, and there are seven or so timeslots. However, as seating space in every venue is limited, we would like to cap registrations per course (venue) to 200 per course, after which either a) the applicant will be informed that they need to register for another course in that timeslot if they apply to a full course, or b) ideal case scenario, the option will be greyed out.

Is this possible using Google Docs Forms at all? If not, is there a free alternative that might do the job properly?