yeah, it’s an astonishing amount of money, by medieval standards a Florin should actually be a bit more than a pound according to my sources, but there must have been some debasement here. I know currency values fluctuated wildly in the 16th century. 90,000 pounds or marks seems an insanely high amount for one small castle, let alone 900,000 or whatever it works out to. That is literally a king’s ransom. I suspect that currency may have been mistranslated. Usually in Poland it would be Złoty which used to be the equivalent of a gulden, and for Germans they would estimate large figures like that typically in marks or gulden, or sometimes thalers or groschen in that area (Silesia).
600,000 Groschen should work out to about 7,500 marks which sounds a lot more reasonable.