The store doesn't do dynamic pricing, each item always costs the same fixed price (unless there's a sale, then it's discounted to a lower fixed price).

The only options are to wait until the chapter is added to the crown store and then buy the collector's pack from the crown store (that's the bonus items, sold separately to the chapter itself), but that won't be until next year.

Alternatively you could try contacting Customer Support and ask if they can refund you for the standard edition so you can buy the collectors edition.