I like searching and finding, and often buying, old publications, eg. documents, reports, books, maps, pamphlets, etc., on Mt. Rainier NP. I love finding good or better original print publications, and I now have a small collecton of them for my work and research on the early years (1890-1915) before and just after the NP designation and later years (1916 to 1940) after the creation of the National Park Service and incorporation of all then existing NP's into the NPS to World War II.
Of late though I'm finding a number of on-line used book resellers offering "Print on Demand" books, or so called books. There is one, paperbackshop-US out of Elk Grove, Illnois which is offering a number of old US government publications in this format, some of which I have or have later original print versions. This company is a US subsidiary of a UK company which sells books, etc. wholesale.
While I won't argue against them, as it's not illegal to resell copies of public doman documents, either as copier copies or digital file print copies, I would argue why buy one unless that's all you want, a copy for some basic purpose and don't mind if it's original or not or even say the quality of the reproduction.
But if it's not what you want, then consider other sources to find an original print copy. Almost all the publications they're offering are still available through used bookststores. Also, I have scanned a number of my original print copies into PDF's for my iPad and Acrobat Pro application, and I offer some of those for free through my Website to share with people. More will be if they're not already available free elsewhere.
Anyway, my point here, is the usual stuff, "Buyer beware."