I often postpone buying technical books because I know they will too soon be dated. Since you're an author and on the other side of the table, what are your tho

I often postpone buying technical books because I know they will too soon be dated. Since you're an author and on the other side of the table, what are your thoughts on offering those who bought the first edition the second book at a good price? Or to sell the book with some sort of subscription, where later editions are available for the subscribers?