Imperial Monarch Sewing Machine

Hello, this sewing machine came into my possetion a few years ago. I would like to get a sence of how much I should insure or sell it for. It is labeled as an Imperial Brand Sewing Machine - Monarch Model. The serial number is c426643 - I was doing some research and this is what I found:

In 1877 took over Imperial Sewing Machine Co. which had been formed as a partnership between Joseph Harris & John Judson in 1873.
Became:
Royal Sewing Machine Co. Ltd Est 1877 - 1882
Became:
Royal Machine Manufacturing Co. Ltd Est 1882 - 1888 +
Machines Made:

• Shakespear 1872 -1888 (also labelled Monarch 1875)

This machine is electric but it looks like it was made in 1875 - perhaps it was converted later on to electric??

It's in pretty good shape and it still works well.

Fair