What?!? Business class for 4 times as much as coach! What a rip-off!!!

My bet: error fare. I can *almost* imagine a $125 one-way coach seat as some sort of crazy teaser fare, sort of like when Spanair did the thing where the first 100 people to show up at a given place and time in Washington D.C. got free tickets to Madrid to celebrate their new route. But there's no way they are intentionally giving away J seats for $500 - even as a promo/teaser.