If you suspect they are BOT's, don't buy from them. Do you know they are they bots, which I would assume by their names, but have you seen these people actually tele-farm? If not just buy from people you know to be legit, or better yet go farm the mats yourself and don't give money to the suspected bots. I see no reason why you should quit the game. Are they somehow affecting your in game experience? Last I checked they were driving prices down for items which in fact helps most other players.

I am in no way a supporter of boting but if this is how you enjoy spending your time playing at least ask SE for a paycheck for being the FFXIV Police on Asura.