Well, first let me address the "Buffy" aspect of this poll...
I've been a supporter of Edens' "Buffy" game since Day 1, and I've been waiting for this supplement since it was first anounced. (It's actually still on my "Special Order" list at my local FLGS!)
And I'd be sorely disappointed if this were to come out in PDF only. I'm not -completely- opposed to PDF but I would always prefer the printed version over the PDF, even if the PDF version was cheaper.
Sure, I -could- print it out and have it bound, but it wouldn't look as cool on my shelf next to all the other Buffy supplements.
So, personally speaking, I'm gonna say I'd pass on a PDF version of this, and I'd have to reconsider buying any further Buffy RPG books from them, if they produce any. (I know it sounds harsh, but I speak with my dollar. I've supoprted them since the beginning, and there are tons of other PRINT books I could buy that are ALSO on my list.)
In general?
I -might- buy a PDF of a book I want, as long as A) It's not for the "Collecting" sake (IE: I like having all my "Exalted" books in one place on my bookshelf), and B) if it was at a substansial (50%+) as opposed to a print book. Though again, I would almost always prefer Print over PDF.