I would have to say reg fee (around $15) for now, due to low results and ovt. However I think with branding it could do much better. I wont leave you there though...I think you should pick up MarkYourCalendars.com. I think this will be more marketable than CalendarMarker.com. Also pick up MarkYourCalendar.org/info as well to receive some (but little) type-in traffic.