[abustamam]

A personal finance author I follow (Ramit Sethi) has a book-buying rule where he has unlimited budget when it comes to buying books because if even one line resonates with you / changes your life then it becomes much more valuable than the $10-$20 you spent on the book. I presume it's aimed towards non-fiction books, but some fiction books can profoundly change your perspective on things, and that's worth the investment too.

I mostly follow that rule, but with the caveat that I must begin reading/skimming it immediately after I buy it (otherwise it will just end up in the list of books "to be read"). Yes this means that I have an embarrassing amount of started books.