Tom,
Never been on e-bay in my life, but maybe you could find something there.
Perhaps a local ham has something gathering dust. Even a foot switch from
an old sewing machine.
I saw something years ago in an old QST "Hints and kinks". A plastic case
from an audio cassette witha small micro switch installed at the hinge
side. Since I had a switch handy, I tried it and it really did work.
Don't think it would hold up for years, but I suppose some guys have home
brewed various foot and hand switches over the years.
Good luck, Steve KW3A