I sold a Leonard Day swivel barrel flintlock in 54 cal/16 gauge about ten years ago for $1,500.00; found it in a pawn shop for $500. The owner brought it back last year, interested in selling it. I found another buyer @ $1,500.00, so its on layaway.
Seems like Track of The Wolf sold one similar for about $2,500 a few months ago. It was designed much like mine. I met Mr Day's son at the NMLRA's Southeastern Rendezvous in 2013, and he indicated then, about a year wait, and $1,600 to start for one like mine.