Hello!
To get cheap hall switches (which are better than reed switches), you can go to
Oppermann-Electronic and look for B 461. It's a hall switch IC, the datasheet can be found
here!.
I've ordered 250 pcs. along with 250 mini neodym magnets (4x4x2 mm) to "magnetize" my 3 manuals and the pedal.
Best regards,
MrFX