+1 on staying plastic as these parts are designed to give, saving more costly components the abuse. A Main Hobbies and Tower Hobbies are my go-to guys along with RC Boca.
I'm running this truck on our pine-forested property, so it goes through some tough stuff. I think I'll stick with the plastic and hopefully avoid anything major.
Dude, you can find some great deals on Ebay and on the traxxas traders forum. I agree, stay away from anything Aluminum on anything to do with the suspension.