If you find stand-alone commercial OCR expensive (as may be the case if you don't have a continuing need for the application) you can try WOCAR first (assuming it is Windows software you want). It is freeware for noncommercial use. It is intended for scanned text and your files must be black and white, not greyscale. The file must be saved in TIFF format. Depending on your images, a basic graphics editor such as IrfanView (also freeware) might/should be able to do the necessary things to convert to files WOCAR can handle.
I just checked and the zip-archive that is available now seems to be the same one I downloaded about five years ago. I don't know what the lack of development means.
<a href="http://ccambien.free.fr/wocar/" target="_blank">http://ccambien.free.fr/wocar/</a>