George,
There are a lot of variables to consider. A decent sized jumper arena (150'X300') can easily cost about $30K to put in. A good reference is "The Equine Arena Handbook" by Robert Malmgren. It'll save you a lot of money and trouble.
Because I'm on sandy loam with no rocks, I was able to take some shortcuts. I don't get perfect drainage on the big one, but it's pretty easy to dry out and I have plenty of equipment to do it with. I can get much better footing out of loam than I can out of pure sand and it's very simular to what we compete on at the "A" and "AA' shows.
We had sand arenas at our old place. They drained well but over the years the sand breaks down and needs to be replaced. That can be a major expense. It's also easy to get it too deep and then you risk injuries. My happiest day was when I got rid of the rotary harrow!
The TR3, the Ground Hog, and a few others are pretty much the top of the line for maintaining an arena (look at what they use at the shows). However, what you actually need depends on the soil conditions you're working with. To build an arena is a different story, there you can be talking about bulldozers, vibratory rollers, etc at one extreme and a chain harrrow at the other.
Mike