I'm all for the Tip Jar
Or, if an author doesn't want to be "tipped", let's call it an
Appreciation Jar..
"You loved the book but bought it used, read it from the library, from a friend, can't afford a new copy?...Show the author your appreciation on his site with what he/she would have received if you had bought an new copy (2 or 3 $ or euro or whatever I believe) or more as you wish!!!".
It could mean something...The message could be at the beginning of each book and ebook with the author web site.
Could be fun, we could see if the editor are really for the protection of authors rights...
Even the pirates would respect that message!
And it's not the "come back to pay later" thing. I don't go back to pay a book, it doesn't mean I didn't like it, just that I completly forgot by the time I actually read it. But I do go to the author's site I like sometimes and would give directly money for books I liked but didn't pay or bought used.