Is it legal for me to charge a fee for dictating or transcribing a specific text?

Say someone wanted their copy of harry potter in the form of an EBOOK but didn't want to spend the time typing it up. Can I charge them a fee to perform that service for them? Technically it's no different than if they wanted to photocopy their version cause it was falling apart. They are just paying me to do the photocopying for them. Clarification please!