How can someone replace binding on an old book?

It can cost a fortune to get a book rebound. You have to use professional binder, if you want a good job. There are two schools of thought, but collectors don't tend to rebind damaged books. There are

exceptions to that - certainly the European books up until the middle of the 19th century were usually issued unbound and they expected that the buyer would have the books bound themselves. So bookbinding was much more common at the time and it was a normal thing for rich people to buy books and then have them bound.

I have had a few books rebound and one of them was in early Japanese English dictionary, which was beautiful 19th century book, but I couldn't open it without cracking the binding. In other words I couldn't use it and I was interested in reading it. I had the rebinding done in Japan. I found a good bookbinder in Japan who was able to cut the cloth of the original and glue it to the new one, so it duplicated the look of the original book, but it was a new binding and it could be opened and used just like a modern book. It was beautiful job, but it cost between $100 and $200, maybe $150 to have that book bound.

Generally book binding is expensive. It's hard to imagine binding a book for less than $100 because you want to do it nicely. But generally, people don't have books rebound. There is no question that it detracts from the value of a rare book. There all kinds of ideas about this, but people usually like to maintain the purity so rebound books sometimes lose their value.