Hello:
"Value" is a personal issue related to your profile.
It is not often that we find sleeper guns at low prices.
More often we see mill-run ones at uninformed, hand-wringing buyer prices.
One issue is the center-fire upper block. While it can be a plus, there are presently four different ones from three makers out there and some DO NOT FIT particular Spencers! The only way to know is to install it and confirm that it seems to fit, cycle and the imprint of the firing pin is centered on the primer. I have seen one c-f block that was way off on important dimensions BECAUSE that particular Spencer was a factory oddball sold to a state militia outfit, not the Federal Gov't. It does cycle original rim-fire rounds, but the C-F block will not interchange without custom machining and welding!
My dealer friends that have been deeply active for twenty-plus years tell me the market for most CW and post CW items has been soft for a year. They are either not buying because they cannot estimate their sales price or are buying and not posting/holding items for sale due to softness.
I have paid premium prices to get what mattered probably only to me, knowing I would not be able to sell for what I paid. But, in these cases, the condition was near mint. These were ones that would not reappear for 30 years. Toys.
I recently declined to buy a couple fine condition, otherwise "one phone call" Spencers (because they were known to me and others) because the "final" asking price was "stupid" high.
The owners ended up receiving considerably less than my quite fair, semi-premium cash offers.
I have no idea why they did that!
Most ordinary Spencers are not going to be investments unless you find superb condition or impeccably documented provenance of a historical nature. I have seen expensive "doctored" originals auctioned by a widely respected house, which makes the authenticity letters bunk. I know who did the doctoring!
Spencer rifles bring more than carbines and 1865's less than 1860's, again, apples-to-apples.
Yes, some have been altered, repaired or enhanced and it takes a REAL PRO to tell. I have seen some of these.
My suggestion is to get photo's and contact David Stavlo at Lodgewood Guns in Wisconsin for his thoughts.
He is an active and credible dealer.
All the best,
El Supremo/Kevin Tinny