Free books are usually very old books out of copyright. You can transfer books from your hard drive to the eReader without problem - I currently have 300 books on my eReader.
More modern ebooks can cost more that the paperback version, but this is improving.
Some libraries have eBooks that can be downloaded free of charge and expire after 14 or 28 days, check with your local library.
So, if you are prepared to deal with the downloading and uploading of ebooks, your friend will not need to access a pc himself.