One of the interesting trends online recently, or at least discovered by me relatively recently, is "bargain bundles" of stuff - games, music, comics, books, that sort of thing. My favourite of these currently is Groupees.com - and they do currently have an sf books bundle. For a mere dollar, you get access to epub and mobi copies of the following:

Snake Agent by Liz Williams
Moving Mars by Greg Bear
Refugee by Piers Anthony
The Blue Hawk by Peter Dickinson
Sunshine by Robin McKinley
Agent of Byzantium by Harry Turtledove


Go up to twelve dollars and another seven books join the party, and if the total purchases reach $15,000, Night Train to Rigel by Timothy Zahn gets thrown in free. So, some good authors there; if you do read ebooks, this is a bit of a bargain, yes?