So basically the best way to get a Griffon's treasure is to send some bait in first, huh. Seems kinda easy to make bank off them, I'd be surprised if any Griffon still had treasure after the first month of them all being turned into monster girls.
ideal monstergirls to get a lot of money: echidna and dragon! collet a lot of treasures. maybe sea monstergirls too can collect it from the sea ground.