I have a manuscript that is a derivative of a mathematical work in the public domain. It is a diamond in the rough which was unpalatable due to its prose. The new manuscript is a modernized and polished up version with added historical context and footnotes.
I'd like to get a publisher to produce an inexpensive paperback version, and hopefully an ebook version as well. Dover immediately came to mind since I know they have a hand in the market for public domain content, as well as inexpensive original content (for example, Robert Ash's books, which are nice.)
Unfortunately, they have been stringing me along with emails for a half year now without ever saying yes or no.
How does one go about seeking alternative publishers of this sort? I've tried a few indexes, but I couldn't figure out how to spot the publishers that serve this sort of niche. The goal is to make an inexpensive print version and/or electronic version.
In case it is helpful to know what I have in mind for 'inexpensive', the figure I have in mind is: no more than $12 USD.
Advice is appreciated: thank you.