I don't think you will find any for free online...
If you go to a Hobby Store that sells gaming supplies you might be able to find "used" copies of the books much more cheaply than buying new. You will also find the the 3E books are a bit more expensive. "Used" books are generally about 1/2 price. Sometimes even lower.
Most of the stores that sell used items are the ones in strip malls. The chain stores sometimes have a small supply of these items. The other thing you could do is look on eBay.
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The line between good and evil is razor sharp. Be careful of misteps,
lest you find yourself spitted upon your own blade.