I would highly recommend the Tamiya TNX for that price range. Stock, it will do close to 40 mph. I've never seen a more user friendly truck. It is very durable and good for bashing and/or racing. It sounds like you already have 7.2v packs and a charger. It even comes with a glow ignitor. You won't need much else to get it going. Here's the best price for it:
http://www.ultimatehobbies.com//p619.html
$309 with free shipping! I know that's a little more than you want to pay. However, it will be worth it. Going cheap never pays off in the end.