1856 rigsbankskilling currently being advertised by LCA for their December auction, with a suggested valuation of $700.
If it were a Copenhagen mint mark (crown) then this might be the case. However, this has the Altona mint mark (orb), and is worth comfortably less than $50 IMO. I paid £1.57 for mine.
It'll be interesting to see if this is corrected prior to the auction, and what it actually sells for.