The ad specifically says "Best Buy's price match policy does not apply to items in this ad and is not valid on prior purchases." This can be found in the red section on the bottom of page 23, right above the HAPPY SHOPPING!.
That sounds to me like it is a no go on price matching. The only way I could see a way around it is to make the purchase before BF, return it during the sale hours with original receipt (to get the full refund, otherwise they will only give you the amount of the sale price at that time), and then somehow convince the BB employee to let you have the item back so that you can repurchase.
No clue if that would work, since I've never tried it. To me, it sounds very unfair to do this, but I can't say I wouldn't do it if I had to have an item that badly and wanted to save some $. Worse thing that would happen would be that you could return the item on or after BF and get a full refund, but may not be able to repurchase the item.