How to Buy Cheap MapleStory 2 Mesos Safely?

Lots of players want to buy MapleStory 2 Mesos. That is the basic requirement, but sometimes Maplers are puzzled how to buy Cheap MapleStory 2 Mesos and not be scammed among so many MapleStory 2 Mesos sellers. How to buy cheap MapleStory 2 Mesos and not to be cheated in the same time?