Erik,
You may know that some of the Jones books were re-printed in recent years; but not those two and they are very good history of the largest of the Maine narrow Gauge Lines.
Volume Two was printed in an edition of only 500 copies so they are definately in the high priced end of railroad books.
I was lucky enough to be able to borrow a set to read. I have talked to Mr Jones, who says there may be a re-print some day, no date specified.
There is a dealer who specializes in Maine Narrow Gauge who sometimes has them. Try Google!
Ted Miles