Convertors

Scouting out gettign a new and proper Torque Convertor for my Duster. Dynamic sounds like the best thing since sliced bread but the fact he has no prices on his web site scares me. What brands for a street driven car are worth the cash? and What should a guy stay away from? Also with the 284-484 Mopar Purple Shaft and 3.55 gears behind the 340 My quick math says a stall in the area of 2500rpm?