Kindle users don't have to go through Smashwords to get book three and four at half price. I have completed publishing book four through Amazon's kindle publishing service and listed the price at $2.50. Again, you can now download the third and fourth through Whispernet for only five bucks. Unfortunately, I cannot reduce the first two books to $0 through Amazon, but $0.99 isn't bad.
Here are the links:
Red Star Conpsiracy: Book Three in the Onyalum Series
Galactic Checkmate: Book Four in the Onyalum Series
Enjoy!