The center CVD's (drive shafts) went out on mine fairly quickly (8XL, 12020 - 12 cells) and I haven't had problems with the stock diffs....yet. A steel idler gear would be nice as well. As far as $300 range. 8XL is a great start, the controller is a tough one. MGM's are out of that budget range. There are folks who can make much better recommendations on that one.

A few other things you will need are 3 high amp gold plugs, possibly a UBEC/radio battery pack depending on the controller, plugs (Dean's preferable). Soldering iron and wire. So factor those into your budget.