I happen to hate expensive pdfs, mainly because I hate pdfs in the first place. So I tend to get sticker shock about the price at a pretty low dollar figure, and without thinking much about how many pages I'm getting for the dollar.
However, the enormous page count on the Frog God Games Tome of Horrors made me curious, and I took out a calculator. First of all, I took a look at the price per page -- and yes, I don't usually calculate value based on price per page, but it makes some sense here. On the printed book, with 688 pages in the Swords & Wizardry version, the cost per page on $100 is $.145. As a comparison, take a 128 page book being sold for $25, which is a pretty good price. The comparable price per page is actually higher than it is for Tome, at $.195. In other words, while it's perhaps not a super blow-out bargain, Tome of Horrors, even with the high sticker price, is actually a better deal than one ordinarily finds. The OSR has cheaper books out there, but ToH isn't at much of a premium, especially since it has binding that is sewn in 16 page signatures, a way higher binding quality than lulu.
The pdf is actually an enormous bargain, as I discovered. Take an OSR module priced at $3.30 for 32 pages -- this is REALLY cheap, because they can run $4.95 for only 16 pages. But let's make the comparison based on the really well-priced module. The price per page on this module is $.103. By comparison, the Tome of Horrors pdf, at $29.99 for those 688 pages, has a per page cost of $.043 per page. In other words, the price per page on the pdf of the Tome of Horrors is an incredibly good value compared to going prices in the OSR. It's less than half the expected price (and that's the expected price on a really inexpensive module, too).
So it probably depends on how much one hates (or loves) pdfs, and how you would value a module as compared to a monster reference book, but overall I just got a lot happier about the pdf price on ToH. Up until now, I was getting sticker shock because the total number is higher than I expect to see for a pdf, but it's actually really, really cheap when it's compared page by page.
Full disclosure: I think virtually everyone reading my blog knows that I'm working with Frog God Games on the Swords & Wizardry materials, so this is not an objective observer's view. But it's the view of a guy who doesn't set the pricing levels. I just got more comfortable with them, being someone who still has a tendency to value things using 1980 dollars instead of 2011 dollars.
And quick warning -- if you go to the FGG page and order the pdf, MAKE SURE you're hitting the button for the Swords & Wizardry version. The Pathfinder and Swords & Wizardry buttons are on the same page right next to each other.