I ran gun shows for 36 years. Most of the dealers don't want to carry traditional BP guns because they are hard to sell. Not a lot of interest. The exception might be the revolvers. Most dealers with traditional BP guns are willing to bargain so they can get them of their inventory.
One factor in the price of c&b pistols might be that they are unregulated in most jurisdictions. Look on the internet, you will find several videos on the question of c&b pistols for home defense in places where other options are prohibited. A sign of the times, I guess.
IronHand