I dunno 'bout "cheap" but there are at least 2 well regarded products:
SharpEye2 - http://www.visiv.co.uk/
and
Photoscore 5 - http://www.neuratron.com/photoscore.htm

Check the release levels (Ultimate vs lite etc.) as not all will output as MIDI

The Photoscore product uses 2 recognition engines; The "Omniscore Photoscore" engine AND the "Lizst music scanning engine" which is used by SharEye. Best of both worlds maybe?

I have used SharpEye2 to great effect, but I've not looked at Photoscore. With SharpEye2 I found the best technique was to fix any scanning errors PRIOR to export. This is obvious if you want to import MIDI to BIAB, but I was exporting to MusicXML for import to Noteworthy Composer 2 (there is a user tool to do the import) and in this case I could have done corrections in NWC. I just found it was somewhat easier to correct in SharpEye first.

Some things to remember:
  • The better the original the better the scan result.
  • DON'T scan in colour - Monochrome (1 bit) is best, greyscale if you must.
  • Don't go overboard on resolution - around 200 dpi usually works well - higher resolutions like 1200 dpi are just a waste of disk space and you end up with lots of extraneous dots that need to be interpreted - experiment to find your best settings.
  • Printed scores work better than handwritten scores.
  • Sometimes it's faster to simply enter it manually.

--=-- My credo: If it's worth doing, it's worth overdoing - just ask my missus, she'll tell ya laugh --=--
You're only paranoid if you're wrong!