You purchase just the agenda and all the extras, i.e., refills, pens, etc., are purchased separately. I think depending on what refill you buy (if you opt to go with the LV refills), you get just the calendar refill or the calendars and the address book. At least that's what I remember when I bought my first refill. Kind of expensive IMO, but I was excited and I kind of splurged. The small Filofax refills work just as well. The small Kate Spade refills are pretty too and fit perfectly in the small ring agendas.
Sometimes I carry two--one as an actual planner and one as a wallet (slip in some plastic card holders, zipper pouch, and you're all set). I have the small ones--damier azur, damier ebony, mono koala w/ pink interior, and white MC. (Can you tell I love agendas?)