Should i put anything for "books and materials not required to be purchased from the school" if i dont know the total amount they cost me?

You must to be able to substantiate any amounts you claim on your tax return.  Look for receipts or other proof of the actual amount you paid or the IRS will make you pay back the exact amount of the tax benefit you received from your rough estimates.

For undergrads, the  amount of qualified expenses need to claim the maximum American Opportunity Credit (AOTC) is $4000.  You may already have that much in tuition and fees. 

Grad students need $10K to get the maximum Lifetime Learning Credit (LLC). Books and other course materials are not qualified expenses for the LLC.