Well, traxxas has made it very easy for someone new to run any of their nitro rigs. The ez-start makes it just that, easy.

That thing makes nitro tuning much more forgiving. It will start a rig that isn't tuned right and help you along.
Sounds like your on the right track. The stampede is a good little truck. Has the simplicity of a 2wd ST (like the xxx-nt or rc10gt), but has more ground clearance and a bit more brute strength. Definitely a rig that isn't intended for racing or finesse, all about the bashing!
By simplicity, the trans is fairly simple and it's 2wd. That in itself will make it a bit squirrelly to drive, especially on loose stuff, but in the grass and on pavement, you should do just fine.
With handling in mind, you might want to look into a HPI MT2. Costs a bit more, but it's still light, simple to work on and a generally good rig with decent parts support.
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXSMG2&P=ML
$339 vs the stampedes $269.
But really, tower has a coupon list that would knock $30 off the MT2 and $25 off the stampede. So it may put the MT2 closer to your price range.
The coupons are on the main page:
http://www.towerhobbies.com/
Either the stampede or MT are great starter rigs, with the stampede being the easier of the two, just the less agile for handling.
When you feel it's time to step up a bit, you can decide what you want later. If you find you like big air, brute force and the ability to run over anything, then a LST2 or savage may be what your looking for. If you like the quickness but still like toughness, maybe a 1/8 scale buggy.