Steel crank. Supersprox rear if you want something that is relatively light and will last. If you want something that is light and relatively cheap, go aluminum rear; Driven or Rethal; I just buy whatever is the cheapest as long as they are not made by Vortex :rofl.
Shop around for combo deals and compare prices on ebay also.
What are you doing interms of gearing changes? Just wondering. Take are look at the sticky, I got some gearing info in there if you are interested.
Have fun!