There is no cap because they request that you spend over $500 US Dollars every event for the Real reward. Captain Shinji for example cost 22250 Gold after doing as much as possible for free that's about $400. Hyorinmaru cost about $25000 after doing as much as possible for free.
To buy the Deed for the Manor cost $75 US Dollars(3000 gold) This game is not F2P if you want anything considered good.