For $400
You can get quite a lot.
Look into 3Racing, TC4, used TC5, Tamiya TA05 TA06, Vettera, Ofna JL series.
Those chassis are all under $150-250 depending on Exotic parts. Also some of them are also Race worthy once you wanna race instead.
Electronic wise.
Hobbywing 80A or More Brushless systems Combo $75-150
Radio wise stick to 2.4Ghz $35-65 Ebay or used
Savox MG or something similar $35-65
So the last expensive thing would be Lipo but you may get away with RTR nimh that some of these come with. And save up for Lipo and Charger. $20-35 per battery $65-150 for a good charger.
Stick to Brushless (10.5-17.5) Less maintaining more play, Spend it once and be done with it don't keep on buying motors.
Same with Radio 2.4ghz = no running away cars.
Servo wise stick with Metal Gear Servos again low maintaining time more fun.
Sorry about the late reply... we are restructuring the website.