Robert Bevan Sale - Caverns and Creatures: Volume I (Books 1 - 4) - $.99 - Kindle Edition. D6 books also $0.99
The first 4 books in the series are .99. There are other books in the series, the D6 books, which are a collection of 6 short side stories put into one book on sale for .99 also. They are listed below. Normally each short story is $2.99 and each D6 book is $6.99. Audible narration is also available for some of them.