If your mission is on-road driving 90% of the time then get something built for on road driving that you can take off road 10% of the time. Driving through grass and dirt is hardly off-road driving and I've taken a rental Sebring convertible all over a Florida cattle ranch for a week for spur of the moment hog hunt. It's not an off road vehicle but it'll drive in grass.
I realize budget is a major issue and a regular automobile isn't likely to be in the cards however make sure you familiarize yourself with legal requirements to take such a buggy on the road. (how much land you own can actually effect whether or not it's farm equipment sort of thing) General common sense items like what you'll need to do to not scare grandma driving up the street and how not to get crossed up with the law. Before you break the rules you're supposed to know them so educate yourself first especially if your main mission will be road use. I don't know what they are in Georgia.
Like Skuzzy said you'll eat up your off road tires very quickly driving on paved roads. They're loud, they don't handle well, they're not meant for it and they'll be gone before you know it. Look into road tires with a relatively aggressive tread pattern that can get you buy driving through your yard if that's all you're going to be doing with it.
You might get a cheap golf cart somewhere too but even those are going to probably be over your budget.
