My question is what is the best ways to put this to an end. Because from his profile I sees lot of tags.
The only way to stop this is if theymos decide that selling accounts are against forum rules but since that is unlikely to happen, nothing can be done really other than tagging them. After all, this is not the first time we see offers like that, with the only difference that they are rarely posted in meta.
And yeah, account prices are set so low on purpose to lure gullible ones thinking they can get accounts that cheap. Yes I think the same as well because it's easier way to lure lazy newbies who wants to grow overnight with the legendary rank to be lured or deceived into sending funds while they got scammed for ignorance.