So, in yesterday's Developer's Diary # 37 we learnt the following.

EARLY ACCESS 15th of NOV?

The 11th of November the initial pre-order program will shut down. A few days after that Early Access for Premium pre-buyers (a.k.a Founders) will open.

After this initial pre-order program is closed, we will only be offered a "new" Premium Edition for the price of $94.99.

Purchasing it will instantly grant the owner an invitation to the early access program, but unfortunately it will not provide them with bonuses and special community status of the Founders (those who pre-ordered before 11th of Nov) 

Final launch will be spring 2014; $59,99 for Standard edition and $99,99 for Premium edition. That means of course that the offer that stands now for initial Premium at $89,99 is really a bargain price-wise, it will grant buyers early access PLUS all the bonus stuff that is connected with this offer.

So if you are sure that you will buy BoS eventually, there is really no reason not to buy the Premium edition before 11th of November, unless you have issues with pre-ordering as a concept or any other "marketing choices" the studio has made.

More info here.