If you've got an e-book reader, here's how to fill it up with your favourite digital books. And some of them are free.

In most cases you'll need to hook up to a PC or laptop to get hold of content to read on your e-book device. Both Amazon and Apple are incentivising publishers to offer their authors' titles as e-books with attractive revenue deals, and have around 70 publishing houses signed up.

You don't necessarily need to pay for books, however. You can grab digital extracts of books from Lovereading.co.uk and by going to the author or publisher websites, while BooksOnBoard.com offers a selection of free Harlequin romances and a range of cut-price titles. It’s worth signing up for newsletters from specific publishing houses whose authors you enjoy – or even following them on Twitter.

For recently released paperbacks by internationally known authors, you're likely to pay around £8 a time – a similar price, in other words, to buying a physical copy from a bookshop. Not all e-books are as expensive, however. Waterstone’s sells paperback fiction and non-fiction for around £9 a title, but its classic e-books – out-of-copyright books nicely repackaged – are just £4.50 to £5.

There's also The Book People, which sells the latest ebooks as well as paperbacks at competitive prices.

Special offers can also be found, particularly if you're on the hunt for bodice rippers and raunchy romances. Free titles you can download tend to be first-time novelists and those without established agents.

WHSmith's (whsmith.co.uk) pricing is similar, while Foyles' most popular titles tend to be more expensive. You will pay £16 for Hilary Mantel's Booker Prize-winning Wolf Hall, for example – the same as if you were buying a hardback copy.

An advanced search on the Foyles site allows you to browse through its 77,000-strong e-books list, where you'll find some titles at paperback prices and some educational and religious studies ones for £3 or £4. This list includes audiobooks.

Audiobooks

If audiobooks also interest you, the two main sources are Amazon-owned Audible.co.uk and Audiobooks.co.uk. The former operates on a subscription basis, where the first three months cost £3.99 each and you then pay £7.99. In return you get heavy discounts. Full-price audiobooks cost around £12 to £19.

The Audio Book Store offers good bundled deals – £25 for 10 Penguin Classics on CD, while downloadable audiobooks cost around £10 each.

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If you've got an e-book reader, here's how to fill it up with your favourite digital books. And some of them are free.

E-book offers

If you’re looking for free e-books, a number of sites can oblige. Lots and lots of marketing books and offers of advice on how to improve your lot are now offered as freely downloadable e-books. The low overheads involved are a marketeer’s dream. Search Amazon, which you might expect to offer e-books given the apparent success of its Kindle e-book reader, and you’ll find title after title offering to explain just how to make money from e-books.

Other sources provide advice on everything from learning a language to how to play the guitar. The ebookdirectory.com portal provides links to many such resources.

Feedbooks.com offers perhaps the best of both worlds – a generous list of works you'll recognise, plus recommended titles you probably haven't encountered before.

Lending library

A relatively new development is an e-book lending library. Sony suggests it on its eBook Reader site: http://www.sony.co.uk/hub/reader-ebook/5/4, while additional resources are listed at Overdrive's site and at search.overdrive.com.

This puts you in touch with the public lending-library network and allows you to borrow digital versions of the books they possess. As with commercially bought e-books, these books are protected by DRM software to prevent them being unlawfully copied or distributed.

Finally, don’t forget Apple's iTunes Store where you’ll find free or inexpensive titles. We quite like the self-scrolling Great Books library that you can download to the iPhone, which is just as useful on the iPad. It cost £2.99, comes with a 200-strong book list of classics and is frequently updated.

See also: Group test: what's the best e-Book reader

See also: Apple iPad vs Amazon Kindle

See all e-book readers reviews