I've been wondering what the price of the planned Big Band add-on will be...but I've guessed that it's going to be quite expensive and that there will be two options - as a standalone plugin for a higher price and one that adds on to GPO for a lower price.
I'm guessing the price at $499 for the standalone version and $399 for the GPO add-on version. Seeing as though a jazz band is so damned hard to sample brass and horns in that playing style, I would easily understand if Big Band went for even double these prices - say $999 and $799!
I personally expect the prices to be pretty steep - at least $400. Maybe I'll be surprised, but a jazz band instrument set is a very, very heavy undertaking, much much harder than an orchestra since the basic articulations are quite easy with an orchestral setting - but when you go for jazz articulations you're looking at a much bigger monster. As far as size on disk goes, GPO is approx 2GB then I'd estimate the big band add on at about 6-10GB, 6GB minimum.