If it's a127, then it's a run of the mill machine in the basic treadle cabinet that is missing parts. In my area, it would be worth $50- $100, and that is if you get someone that is uniformed willing to part with a lot of money.
It's like about the cheapest machine and cabinet one could get from Singer at the time, and since then it's been modified quite a bit. So it's not really worth anything to a collector, only someone that likes it and wants to sew with it. It should be very good as a usable machine.
BTW- if they arleady had the table and wanted electric - why not remove the treadle? I'm sure at the time the owner thought it was just a piece of old "technology" and would have never guessed that some day, near 100 years in the future, someone would want a treadle machine! And I know first hand it's a pain to try to sew with the electric pedal on top of the treadle pedal, even if you wire the treadle so it can't move.