If your going to spend $170 just for the shaft and head, I got a used Foredom variable speed, 0-15000 rpm , 1/3 hp TX series on Ebay with the shaft and head for $250, basically new. Not for sustained heavy industrial use , but can do very fine work with little vibration plus it can do anything a Dremel can do but better/cooler/ much more power.
For sustained heavy duty use follow dr clyde's recommendations.