Seriously, who really needs the warning? From the posts here, this guy will either offend or insult you almost immediately. I can't see anyone putting up with that.
And, if you are going to put up a warning post, DO NOT call someone a scammer unless you have proof. From this post, all I can see is the dude overpriced his stuff, is rude, and likely not the most educated person in the world. Nothing has been posted to suggest he has scammed anyone. Don't let your dislike for someone cause you to make libelous statements. Frankly, it makes you look just as bad in my eyes