LEGO 4785 Black Castle was a 380 piece Duplo set with 6 Duplo figures released in 2005. It includes one good knight on a DUPLO dragon and five evil dragon knights. The current value for a new and sealed Black Castle is estimated around $2,454 today with current average yearly gain of about 13% but will level off in the next year closer to a 5% annual growth. The current used prices for Black Castle can be found in the range of $167 and $368 depending on the set's condition, with an average price of $168 if it is in good overall condition.