Thanks for the thread Grant. I sometimes don't mind trying to answer honest questions about value when it's an established member on the forum but sometimes it gets old when a person is on here for the first time and just wants to know what to unload their Grandma's/Aunt's etc. machine for and we know we'll never see them again.
Grant I would say your rule of thumb on price is right on.
Also, with certain rare exceptions, no one is going to get rich off an old sewing machine. It's a sad fact of life that supply is way in excess of demand.
I have over 20 machines (small time around here

) and I haven't paid more than $30 for any of them.
Rodney