Well, if you like the maxxes on that page, the new T-maxx will be coming out in a week or so.
http://www.towerhobbies.com/products...as/trac54.html
That will be much improved over the old T, but I can't say how easy to tune the engine is because they are brand new. You'll need:
Fuel (10%-20% Top Fuel from Traxxas)
Application of the decals
Fuel Bottle to fill tank
6 Cell Battery for Easy Starter
Charger for 6 cell battery
CA glue to attach tires to the rims
I guess that comes out to over your $400 limit, but it would be worth it. Plan on catching the upgrade bug and dumping some more cash into it after you get it though
I also recommend running 20% fuel for a little more power.
If you have any other questions, ask away
