Re: the Silvertone phonograph.  I believe this was a machine made for
Sears, Roebuck and Co. as a relatively cheap machine for a mass market.
I read that Silvertone records were available from 1916 and that they
were made by the Columbia Phonograph Co. for Sears.  So it is a safe
guess that Columbia also made the Silvertone.

A Silvertone's value?   Like items in the mechanical music field that
we are more used to reading about on the MMD, it depends on condition,
how well it works, and who's there on that day.  I assume yours has an
external horn, and as a generic machine of this era, I would expect it
to fetch around $500.   Condition is everything though; so who knows?

Hope this helps,
Paul Morris