As you may know, if you have played this game for quite a while. This stone originally costs approximatly 200m. And now? It dropped to 70m-75m, it become a worthless stones.
With 22x% drop rate, I usually hunt 1 stone in 1-2 hours. Seriously.... 1-2 hours for 1 stone which costs... $0.7. If you work you can at least make $10 per hour. Hunting stones used to me quite profitable for me as each stone can sell for 200m. But now? Don't hunt anymore! It is not worth your time hunting this stone anymore.
Hunting EB also another worthless activity, hunting purple cube now each purple cube worth only 55m. And yellow cube 40m. The time taken to get those cubes ... ? Not worth, usually after 5 ebs you will get 1 yellow cube or purple cube. But... worth? Nope.
Seriously, there is no easy way to farm mesos in game for free now. Plus, there is no mesos bag in sale in the cash shop. Also, mesos sellers are all out of stock of their mesos stocks. Mesos become a super rare and precious thing in this game now. Now you can sell $12/b.
Soon, you will see $20/b... because mesos keep getting swept away by the star force system without returning to the market.
