A new product comes with a price the maker set. Architectural salvage pricing works differently: the maker is long gone and never pictured the piece being sold twice. So how does a hundred-year-old part get a price at all? Not out of the air. A few real factors set it, and they're worth knowing whether you're buying or just wondering why that sconce costs what it does.
Scarcity and condition
Start with how many are left. The supply of any original part is fixed and only shrinks, so the fewer sound examples are left, the more it brings, for the plain reason that no more are coming. A common shade stays cheap. A shade down to its last survivors doesn't.
Condition and completeness can change a price sharply. A fixture that's whole, sound, and needs little is worth far more than the same fixture cracked, missing parts, or facing heavy work. Restorability rides alongside: a piece that comes back cleanly is worth more than one whose repair is a gamble. Much of what a good shop adds lives right here, in the work between a rough survivor and a sound, usable piece.
Demand and the taste cycle
Demand is the last piece, and it's where the taste cycle shows up on the tag. A style buyers want right now brings more; a style out of favor sits cheaper, sometimes well below what it'll bring when its decade comes back around. Two near-identical sconces can price differently because one style is having its moment and the other isn't.
There's no formula to run here. It's judgment, weighing scarcity against condition against demand for the exact piece in hand, which is why pricing rewards a dealer who has handled the material.
Salvager's Note — what moves a salvage price: scarcity (how few survive intact), condition and completeness (whole beats broken by a wide margin), restorability (a clean fix beats a gamble), and demand (whether the style is having its decade).