The price does seem high. A Winchester 1873 in fine original condition, with most of the finish reasonably intact, can be had for about $5,000 these days, though owners of such rifles are generally disinclined to fire them.
The work of Turnbull’s company is generally of very high quality, though they don’t really replicate the original Winchester finishes in all cases. Their case hardening generally has more blue colouration overall, which seems to be the fashion these days. And the loading gate of this rifle should be nitre blued. This particular rifle is somewhat restrained, but other Turnbull restorations seem garishly “over the top”.
I think that as time goes by, restoration—when done correctly (most aren’t)—will be more accepted, even by collectors. Often the rifles selected for restoration are in rather sad condition, so restoration not only makes them beautiful and like new again, but also makes them more attractive to any-one.
One can get a better deal than this. A good, solid, unaltered 1873, with no finish or “brown” finish can be had for $2,000 to $3,000, and a top-level restoration of such a rifle by Mike Hunter, for example—
http://www.mikehunterrestorations.com/—who does replicate original finishes perfectly, will add $2,000 or a bit more. One could start with a lesser condition rifle, but restoration might cost more. There is probably an ideal level of initial condition that results in the lowest combined cost of purchase and restoration. If one can get a good candidate rifle for less, or if one already owns one, then the deal gets even better.
Thus, for about $4,000 to $5,000, one can have an original 1873 in essentially factory new condition—with better finish than the $5,000 original condition examples, on which the rust blue on the barrel and magazine (for example) even if unmarred will have turned somewhat brown, and on which the case hardening will have faded.
There is another thing to keep in mind about restoration. Very often, important parts are replaced by modern replicas, especially in high production shops like Turnbull’s. For example, the stocks of the rifle on GunBroker are clearly new replacements, albeit finished like originals by the look of them. The screws appear new as well, and other small—or even large—parts may be replacements, too. A careful restorer can save more of the originality of a rifle—though this can add to the cost.
Although there is an undoubted extra historical connexion in antique firearms that remain in original condition, I think there is a big difference between working rifles that were esteemed and well cared for (and from which the loss of finish does not detract), and the far more common survivors of decades of neglect or even abuse. The former display actual, substantial history in their appearance, and the latter, only the passage of time amidst diminished circumstances. I certainly don’t think there is anything wrong with top-quality restoration of the latter. It’s a kindness to a fine old rifle that wants to look its best, again.