Anyone know where I can get textbooks, or at least portions, in a PDF online? (for free)

Have you tried looking on torrent sites like kickass or demonoid or http://www.freebookspot.es/

filestube, only not so much anymore. I used to be able to find all sorts of ebooks for free, but if you type “DRM-free textbooks” in a search you can usually find a good site that at least has them for cheap, and can go onto any device.

Usually I type “Name Of Book pdf free [replace ‘free’ with ‘download’ sometimes]” in google, and search for about 10–20 minutes. Eventually you find one on a forum where someone bought it, deleted the license, and uploaded it for his friends.

Check if Google Books has a preview of it. If not, head to your library and/or bookstore and read over the copies there if they have them.

@unused_bagels I can still find many ebooks on Filestube. I found one of mine just 2 days ago.

Check your campus library? 99% of the time they rent some out for a few hours or so, easily enough time to make a copy of the pages you need.

I agree with @Aethelflaed, try Google books. Also, Amazon lets you see parts of some books (click on Look Inside if the option is available). You won’t get access to the whole book but you might be lucky and get the part you need. Good luck.