Antique shops usually price the stuff above even brick-and-mortar camera stores. There's one in Manhattan that has an 8x10 Korona for $700 and a Bessa with Color Heliar for $400. They weren't willing to negotiate to anything realistic.
I have, however, bought some darkroom accessories for decent prices, since most folks have no idea what they are for.
I always look, but rarely find anything useful, for anywhere near market value.