It's deductible gives a high value for hardback books of $7.00 and a medium value of $4.00. That's seems high. Can I really claim that and be OK?

That does seem high See this:

http://www.goodwill.org/wp-content/uploads/2010/12/Donation_Valuation_Guide.pdf

https://satruck.org/Home/DonationValueGuide#household-goods

So, if you pay retail prices for books and music...say $28.00 for a hardback book, you really think it is unreasonable to claim 25% of purchase price as a tax deduction? Remember thrift stores resell to people who will resell that book on Amazon for $10-$15.00 or more if it is in demand. Moreover, thrift stores price to move volume but in many cases they pick out higher value items and sell them separately, so don't let their $1-$4 selling prices determine your charitable deduction.