I agree, this would be difficult. A 150 would be large enough but a very stable tank, with lots of oxygen, and feeding 2-5x per day small feedings, even nori would work as well, would be best.
I have great success with Leopards but I wouldn't drop that kind of coin on a difficult to keep fish. I know that it is guaranteed for 14 days but it's a huge risk.
I would avoid this until you're a "seasoned veteran" and can keep difficult wrasse. I have several expert only and difficult wrasses (Radiant wrasse, Male Blue Star Leopard, Female blue star leopards, potters wrasse, ornate leopard, black leopard, regular leopard, and red coris wrasse) but I still probably wouldn't try even if money was no object.