Kolath wrote: Now that GW doesn't sell any old books I guess the only source is PDFs or yard sales/ebay?
You have plenty of options other illegal downloads.
eBay is a good place to start. Second-hand bookshops are worth a try, as are the Swap sections of forums, or Bartertown.
You local games store may still have copies of old books, and if they don't, some of the players might. Some stores have a noticeboard that serves a similar function to a forum swap-shop.
You can also try newspaper classifieds, or hunt around online for webstores selling older material.