Some publishers have gone as far as giving a good chunk of their products away as a free preview. I'm not talking a dozen or two pages, more in the range of 60+. Certainly enough to get an idea if the book full bok is right for you, and a great way to borrow and steal freely available material for your own campaign.
Interface Zero (Savage Worlds edition), Players Guide Beta test From Gun Metal Games is the first 3 chapters (over 60 pages) of cyberpunk for your Savage Worlds gaming. Your character generation rules are here. Also works well as a Player's Character Creating Guide so all the players aren't looking over the GM's shoulder.
Savage Suzerain Play Now, For Free From Savage Mojo is nearly 100 pages. For this I'm gonna borrow in the publisher's own words:
Not sure whether you want your characters to be a pantheon in the making? Before you invest in some major gaming pleasure… Product Contains: A 98 page full color, hi-resolution PDF. It is a large download file and art intensive. Inside are 24 pre-generated character sheets for six characters at four power levels, plus all the universe background and game rules needed to play those characters at any of the power levels. There’s also a detailed description of how those characters were made from our resident Savage Worlds guru, Alan Bundock and five One Sheet adventures to get your GM started.
Not too shabby for the gamer on the budget.
Then again, there's the game I've been waiting for for ages, and I've already plunked 90 bucks down for the dead tree / PDF preorder (and its not savage Worlds, its Fate / SotC):
The Dresden Files RPG Preview: Nevermore From Evil Hat Productions, LLC. If you've read ANY of the books in the Dresden series you'll know why this excites me. If you haven't, you owe it to yourself to start. I already have the PDFs from the preorder... the 2 books combine for some 900 pages or so... time for me to take a week off sick from work to start reading. ;)