Forget about that smart cr*p, way overpriced, like everything Spektrum, but even more so.
The pack you get with the associated won't last 15 minutes of runtime, and the charger is a joke. No storage mode if I can see right.
You can get a good 3s 5Ah battery for 30ish bucks and a decent...
400 bucks is a tight budget. Maybe the Arrma 3s blx line would be a good choice. You'll need a couple of Lipo packs and a charger, and some basic tools too.
Nitro is unreliable compared to electric nowadays.