I don’t know how much we should trust this but Sigma Bielorussia is the first Sigma site that unveils the pricing of the new 50mmf /1.4 ART lens. it should cost around $790. The lens will ship in May. $790 would be a super low price for a lens whos aim is to almost match the Zeiss Otus lens ($3999) performance!
Link found via Sigma-Rumors.