I suspect a pricing error at Tor.
Impulse
The third in Steven Gould's Jumper series (4th if you count Griffin's Story, the movie tie-in).
The Hermetic Millenia, the sequel to John C Wright's Count to a Trillion.
Farside
Loosely tied to Ben Bova's Moonrise series.
I don't know how long they will remain at this price at Amazon. All are very new books (I think February release), and I picked them up at B&N for $1.99 the other day, but they're all now $11.99 or $12.99 at B&N and Kobo. Since they're all from Tor, should be DRM-free though and convertable to ePub.