Spend the money to get the new books. Knowledge is Power
I strongly recommend getting them from Bill Cohenour. He has been very helpful to me when I have questions about he strikes.
Getting the newer books gives you the newer information. When Silver was $40 an ounce the prices reflected that, now you can see how the prices have changed. Some strikes still command larger prices, some have become common.
You will never regret buying the new books for the new information.