I recommend www.inftyreader.org. They have a trial version, with long enough trial period to do a big project. I've used InftyReader on a flakey old laptop and it did a pretty good job for a math book reissue. It took about half an hour or so to do each 40 page bundle of the disassembled book. It made systematic errors in the tex, many of which I was able to correct with some awk commands, but of course I still had to go through the whole thing tediously. I was not going for perfection, but just for something editable, and I think it came out better than required for this purpose.