25/04/2014 07:40 BST | Updated 24/06/2014 06:59 BST

What is the Real Value of a Book?

How much is a book worth to you? Of course there is a difference between the value of the knowledge or enjoyment you might get from reading a book and the cost of the physical artefact.

But then again, these days books are often not physical at all, just a stream of data beamed direct to your Kindle or iPad.

I bought a new book today. Written by Philippe Legrain, 'European Spring: Why Our Economies and Politics are in a Mess - and How to Put Them Right' sounds like a topical read for anyone following the news about Europe at present.

But there is something else that is interesting about this book. The physical book costs £12.99, but the Kindle version is just £2.99 - I bought the Kindle version because I like to be able to carry a lot of books around with me without breaking my back.

Philippe Legrain can still earn a good royalty from the reduced price e-book because there is no need to print or deliver a physical book, so his own share of that lower price will be much higher.

But some publishers don't seem to be offering e-books at a reduced - or even reasonable - price yet. Another book that was recently published and interested me enough to search it out on Amazon was 'Capital in the Twenty-First Century' by Thomas Piketty.

It has enjoyed some good reviews, but when I saw that Amazon wants £29.95 for the physical book and £17.97 for the e-book I just closed the page. They want eighteen quid for a download? Eighteen quid?

Of course I could just go and seek out a pirate version of the book. I'm sure that someone has already ripped the Kindle version of the book and made it freely available on a pirate website, but I'm a writer myself. I know that people who put months of effort into books deserve to get something for their efforts.

But what is the right price when £3 seems to be fair and £18 seems too much?

This is a question the book trade is exploring at present; clearly with differing views depending on which publisher you ask. What is obvious to anyone is that the glut of books available for pennies is not sustainable.

I don't mean the self-published sci-fi novels that feature Star Wars characters on the USS Enterprise - if self-published novels are any good then they will eventually find an audience. I mean that when you can find literature such as Yann Martel's Man-Booker winning 'Life of Pi' on sale for 20p then there is surely something wrong with the system. Admittedly, this book is a bit more expensive now, but was sold for pennies when the movie was released.

The last book I published is available on Amazon for just 99p and there is a good reason for this. I wanted it to be easily available at a very low price so that the message contained in the book would be spread far and wide. Of course I could have just made it free, but when information is completely free the perception is that it has less value. That book has some very good reviews so people seem to value what I said - with some even suggesting that it should be sold at a higher price.

But even this strategy of distributing books at a very low price doesn't always work. A writer got in touch with me recently suggesting that she was writing a book similar to mine and if I sent her a free copy then she might reference my book.

Clearly if every piece of research depended on the author receiving a free copy then our global knowledge base might be a little different. In fact, we might find every new book referencing only those authors prepared to publish and freely distribute their work to journalists and writers. Of course that used to be the job of libraries - remember them?

The only real cost associated with a digital download (once written) is the bandwidth a retail company like Amazon needs to ship the product and this is miniscule for each individual title. But cost cannot be associated with value. Every book still has a potential value to the reader, even if it is digital. Knowledge is still shared when someone downloads a book, but consumers know that the cost of printing and distribution has been removed from the equation. What is a fair price?

Publishers today need to consider that consumers of e-books are going to expect to see a consistently lower price than the physical version of the book. Philippe Legrain's pricing model seems good to me - I bought a copy. Unfortunately it seems that Thomas Piketty's publisher needs to take a few more lessons in capitalism.