I'm booking a similar "magical" deal for November at Coronado Springs and I also plan to get an AP. The great rates for magical deals are possible because they are booked as convention rate hotel rooms and tickets. I asked the magical rep if their discounted tickets can be upgraded to AP and she said they could not. She said I could book room only without buying tickets from them.
Then, I read on All Ears WDW Ticket FAQ that it could be possible to upgrade convention rate tickets. It sounds like you would only get credit for the price paid for the tickets - not the gate price. So no price bridging.
Since there's a chance the tix can't be upgraded, and a chance of no price bridging anyway, I'm just going to buy the AP from WDW. I plan to use my Redcard at Target to save 5% on Disney gift cards to pay for the AP (and hotel).
http://allears.net/pl/ticket.htm#credpass
· Guests wishing to upgrade Magic Your Way Meeting & Convention Tickets to Gate Priced 9-Day, 10-Day or Annual Passes may do so by paying the full price difference between the Magic Your Way Meeting & Convention Ticket price and the ticket of choice. If the Water Park Fun & More visit has been used, then the Guest must purchase a ticket with Water Park Fun & More or a Premium Annual Pass.