The Dark Lord's Handbook is available as a Kindle eBook (UK store, US Store) .

There are free Kindle readers  for most platforms (PC/Mac/phone/tablet) so you don't need a Kindle device to read the book.

The book is available for iBooks through the iTunes store.

A paperback copy is available from Lulu.

For other eBook readers you can buy the ePub, PDF, RTF and LRF formats from Smashwords.

An Italian translation can be found at Fanucci Editore.