The Pandora Sequence by Frank Herbert and Bill Ransom are all on sale:
The Jesus Incident - $2,
Amazon,
B&N and
Kobo
The Lazarus Effect - $3,
Amazon,
B&N and
Kobo
The Ascension Factor - $3,
Amazon,
B&N and
Kobo
The series is a follow-up to another Herbert book:
Destination: Void. But it is not necessary to have read that one to read this trilogy. There's a reason it is not included in the collected volume.
Edit: There's also a collected book. It's $8.50 at
B&N and
Kobo, but
Amazon has it on sale for $2!