I don't know what the vendors will call their sales as we approach the holidays (nor if they will host any specifically for the holidays). However, I have found almost all, if not all, IAP vendors to host sales almost all-year-round (not always on all kits, goods, etc.). Many of their regular prices are already at a discount to PSI and CSUSA.
Not to drive anyone away from IAPs loyal vendors, but Berea, Wooden Whimsies, Wood Turningz, Huts, etc...all run specials each week and publish them weekly (even twice a week) via subscriptions to their email/Internet specials. Moreover, many of our IAP vendors sell Berea and other manufacturers kits at a discount all of the time.
Lastly, someone may host a group buy where discounts can be enjoyed. I hope this helps and doesn't confuse.