Bargain @ $1.99 each from Open Road Media, probably good for at least the next week, and possibly until the end of the month (couponable @ Kobo, should be available in all the standard stores, price good for Canada & US, possibly in other regions as well, etc.):
(ETA: this may only be good until the 22nd; today's ORM newsletter has one of the featured books on this sale listed with that as an expiry date, though they've done that before with another previous sale book which turned out to be good until the end of the month.)
Famous Firsts Sale: Fantastical First Novels from Authors Who Made It, with a very good selection of science fiction, fantasy, and some horror-ish novels from quite well-known writers.
There's Octavia Butler, Tim Powers, George Alec Effinger (generally recommended; I haven't gotten around to reading this one, but I usually like his writing), Ian R. MacLeod, Patricia C. Wrede, R. A. MacAvoy (selected title also recommended, it's a bit dated tech-wise, but I liked it quite a lot when I bought it from Fictionwise years ago), James Morrow, Pamela Sargent, Dave Duncan, and many more award winning/nominated genre authors.
I'll note that the Buzz Aldrin/John Barnes book was part of a previous Humble Bundle, so you might have that already, and IIRC, the Frank Lauria book was an Amazon freebie a couple of years ago from former publisher e-Reads before ORM bought them out, so that's another one you might already have. Also some of the other titles are 1st-in-series works that have money-saving omnibus editions which probably work out to be cheaper with a good coupon.
But it's a pretty nice selection and I'll be picking up a number of titles I don't already own.