I was checking out Ebay and they do have some stuff on there. Wouldn't be a bad idea to get a used one that's in good condition as a spare parts truck or even one for the kids to run if their old enough.
http://www.ebay.com/itm/RC-18T-Team-...item2ed15a4da3
Yes bearings will make it faster and smoother.
http://www.ebay.com/itm/15pcs-TEAM-A...item3a8f916719
here is a stock servo saver, they get broke easy when you hit something hard with one of the front wheels.
http://www.ebay.com/itm/15pcs-TEAM-A...item3a8f916719
CVDs are a good upgrade and you won't have problems with the stock dog bones popping out.
http://www.ebay.com/itm/Steel-Swing-...item2c5edf680b