Instead of Abbyy, which costs money, you can try pdftotext, which is open source - it's a little Windows command line utility, which you can download from
www.xpdfreader.com (it's included in the Xpdf tools). With the -layout option, it gives you a plain text file with line breaks that correspond to the lines in the PDF (doesn't work with all PDF files, though).
You'll still have a lot of editing to do, but with a decent editor and a little knowledge of regular expressions and a tool to convert plain text to epub you should be able to get a reasonably readable epub version in an hour or so. (I have a tool that helps with the process, but like pdftotext it's Windows command line stuff, so I don't know if you're interested.)