I highly doubt that hornetsnest would pay $2710 to get that 271 merit, so if this is anything, he is probably farming accounts and not actually selling merit, or he is not aware of how much they go for. 
I always thought that the reason some users sell merits for as much as $10/each is that some users just want a quick merit to start bounty hunting and $10 isn't such a big amount. But when we start talking about ranking up to Sr, Hero or Legendary, it becomes impossible for anyone to consider spending that much with it.Since trading merit is against the forum rules, shouldn't the accused member/s be reported rather than tagged? I mean what stops them from trading merit even with an active flag and a dozen negative feedback?
Isn't merit trading only against the rules if you are a merit source? I mean, we all agree that it's not a good thing to do, but the consensus from the community that something is not ok is one thing and being officially not allowed is another thing.