Pdx - your project sounds like a great idea.
Here's what I found out about E-Books...there is not enough return for all the effort involved.
Trust me...I've been there.
All railroad based projects are a labor of love - don't expect to get much money back for the work it takes to see a publication all the way to the public.
Here's what I found out - for themes of local or regional interest - have them printed yourself.

Here's the best option I have found.
Have them printed at Printing Center USA in Great Falls
[www.printingcenterusa.com]

Their prices are reasonable and fast [and excellent quality!] - you can get your publications in a week or two.
The best way to send files to them is via PDF format -

Anyway - check them out...and let them know that Dale Jones of Railroads-of-Montana recommended them

Talk to ya later,
Dale Jones
[railroads-of-montana.com]