I have used Kate Spade and tilofax refills both once, but I much prefer LV refills. They are only really expensive if you buy the entire refill every year. If you buy just the calendar pages it's much less. I love the gold edging on the pages too. For me, even though it was more expensive by a bit, it wasn't that much more and the enjoyment is worth the few cents a day extra.
I look at it this way. I use my planner 365 days a year. A refill is around 45-50 dollars. Cost per day is really small, less than $.13 per day, making it sbout $.08 or $.09 per day than Filofax. For a dime a day, I love my LV inserts. The fun of that and seeing the brown LV cover, gold tipped pages, bookmarks, ruler, and little brown address book, French writing (reminding me of tge rich history of the brand) is worth the nickel and a couple of pennies a day extra. While I might save $30 going with a cheaper refill, I know I want be as happy in the daily use of my planner, so it's worth it to me to skip a couple of trips to Starbucks and have more luxurious and real LV gold colored edging and the real thing as far as my inserts.
I got the full insert with maps and address book and all the bells and whistles the first time, and for the last 10 years, just the calendar to save money. I was not happy when I tried to skimp and use Filofax or Kate spade and ended up throwing both out which cost me even more money. But that's just me. Lots of people use and love Filofax. It just didn't make me as happy though and marred the fun of using and enjoying my planner, so it's something to think about.
Congrats though on your agenda!! I recently bought the zippy in this line and love it!