Amazon has some Orbit novellas on sale for $0.99 (regularly $2.99). Here's a search that should find them - just scroll past the free samplers:
http://www.amazon.com/s/ref=sr_st?un...bit&sort=price
Here's a few of the titles:
The Butcher of Anderson Station: A Story of The Expanse - James S.A. Corey
http://www.amazon.com/The-Butcher-An...dp/B0052AHUYM/
Gods of Risk: An Expanse Novella (The Expanse) - James S.A. Corey
http://www.amazon.com/Gods-Risk-Expa...dp/B008CJ241O/
Perfect Shadow: A Night Angel Novella - Brent Weeks
http://www.amazon.com/Perfect-Shadow...dp/B004RQTXDI/
Spirit's Oath: An Eli Monpress Novella (The Legend of Eli Monpress) - Rachel Aaron
http://www.amazon.com/Spirits-Oath-M...dp/B006IIH7WW/
Blooded: A Jessica McClain Novella - Amanda Carlson
http://www.amazon.com/Blooded-Jessic...dp/B0078XGUZQ/
At $3, I think these were overpriced, but for $1, I'll probably bite.
I think they're probably on sale elsewhere, too.