It has to be available as a free HTML document for me to consider buying it.
If the pdf though is close to the paper book in price then I'll forego it because I'll be buying the book too.
Yes, Pathfinder releases most of the rules as a free html, the full books with examples, fluff, and art as cheap pdfs, and then the print copies. Three different tiers with differential pricing and clear implications for the purchaser. To me, that is the model for distribution.Like the Pathfinder SRD? A great resource but I still like the idea of owning the original book, just in electronic format.
No. In fact, I'm the opposite - it needs to be available in print or I won't buy it.
That said, I'll readily agree that anything that can be made available in suitable electronic forms (including, but not limited to, PDFs) should be made available in those forms.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.