Deduct the supporters? Supporters count for $15In theory, sure. In practice, nowhere close.
As a rule of thumb for most forums, only about 10% of your registered users are actually active. We're above that, but even if it's double (and I don't think it is) that would be ~14,000 active users. From that number you'd then have to deduct those that are already supporters and those that wouldn't use the classifieds enough to think the cost was justified and wouldn't pay for a sub. So no, the number isn't anywhere near $720k.

