Its perfect Yes. for the following reasons
Paper Demand is going high
It takes 12 trees to make one ton of 100 percent non-recycled newsprint. Every year 5 Billion tonnes of paper are made. 4.12 Million tree are cut every year for the manufacturing of paper alone.
Hence the cost of paper also shoots up, So Used books are best alternatives.
Anyway someone is going to throw away the book even if its in good condition, why not you can use it.
Publishing Industry also takes keeps increasing the cost of the book, For eg. When I bought the
Current Price of the Same book is Rs. 1200/-
So certainly, Buying used books is way to go.