People would actually buy these, including myself, from other players, especially if they were cheaper than the job change itself.
The thing is though; job changes at level 200 cost way more than 200m to change. People can't sell them for monopoly prices because everyone will just pay the npc. They are forced to compete with the 4th job NPC's prices, as if they were in a competitive economy. I'm asking for them to be tradable precisely for this reason. Because I want job changes to always be around a cheap price range. I hate paying 500m or more to change beyond level 200, but I'll have to if someone thinks they can sell them for more than the price that the npc is offering.
People aren't going to sell job tokens to low levels for 9m because that's stupid lol. They can sell it to high levels who can't afford to fully pay for a 1b maplestory mesos job advancement for little as 200-500m, which is still cheaper than paying the npc to change jobs. The sweet spot for selling them would be where players would actually pay a lot while still being cheaper than paying the npc, but actually make a profit. No one will sell these tokens for below 100m I guaruntee it and no one will buy them unless they're over level 180 where the price to change jobs is too high.
People won't look at your level and say "hmm for you to job change it will be about 10m, so I will sell it to you for 9m," they'll look at the higher levels who have to pay bils to job change and say "hmm these guys are paying 1b to job change, so I think I'll help them out by selling them for, at most, less than 75% of the actual price to change. They'll be happy and I'll also make a huge profit!"
Then there's "that guy" who sees the high levels that are paying 1b to job change and go "They're paying 1b, so let's make the price of these job coins exactly 999,999,999 maplestory mesos! Genius!" and not sell a single token because people would rather buy from an npc than give into "that guy's" greed.
These tokens also aren't easily obtainable. I got two of them but thats out of more than 70 tickets ($70).
And also if people didn't want to pay even that much, they can just wait for free tokens to come from coin shops.