OK, thanks for the thoughtful comments.
Excellent articles, and even better prices on those fireplace screens!
I don't really know the difference between embroidery floss and silk, but this seems a bit less "shiny" than silk, while being a bit brighter than most embroidery that you see from back then.
KC, your evaluation of machine made with a bit of handwork thrown in and the reasons why makes sense.
In the meantime, I've been doing research on frames. This frame, although less elaborated than some, still features significant (almost shadow box) depth, walnut burl panels, gilt, and ebonized sections. From what I can tell there's no reason to think that this frame couldn't date to 1880-1900 or so, as these features are commonly found in pier mirrors and other such furniture of the time. Perhaps a somewhat "plain" frame was desired to better show off the crewel work within.
This piece is pretty large, and so is the frame. It's interesting to think that the piece may have been intended to be a fireplace screen.
So now the kicker: Does $150 replacement value sound realistic? Higher? Lower?
