As an avid collector of all FFG Star Wars material (who also missed the in store event sadly), I'd like to buy a copy of the Rebellion Day pack.

Preferably without paying a fortune on eBay.

It's going to be on sale, right?

My guess is probably not. At some point in the future it's possible they might make it available as a downloadable PDF. The precedent there is "Under a Black Sun", which I believe was a Free RPG Day module and then later became a downloadable PDF.

There's no indication either way about whether that will happen but it's possible.

You might want to try just calling FFG's sales line and asking if they have any copies left. Since the event is over, they might be willing to sell whatever they have left to civilians, just to unload them and make some money. Couldn't hurt to ask, at any rate