Remote controlled truck specifically.
I want to use the RC truck to tow balloons and shoot at them as they bobble in the wind.
Maybe mix up some different color balloons for shoot and don't shoot.
That type of thing.

I've been looking at some ads and auctions, but I don't know enough to descriminate between a deal and some crap that wont serve my purpose.
I want the controls to work at atleast 100 meters.
It has to handle the grass and gravel and ash and sand without getting stuck all the time.

I don't really care about the body.
I'm already resigned to cutting it up and installing a base for a whip antenna or something, to keep the balloons high and away from the vehicle.

If I knew what the hell I was looking for, there's probably deals to be had.
It's the type of thing that does a lot of sitting around collecting dust for most of the folks that own them.

Thanks in advance for any help.

Remind me to bring my remote controlled car next time we get together.  You're right, it is something that sits around collecting dust too much.  I need to take it out more.  Personally I like the electric vehicles - easier (cheaper) to get into and don't make much noise to annoy the neighbors.  Rechargable batteries have come a long way in the past 10 years.  Nitro will get you more power and speed for more $$ and noise.

For what you describe a monster truck type would likely be your best bet.  You'd need a RTR (ready to run) kit that comes with truck and radio along with a couple of battery packs and a peak charger.  $250 would be my guess, $200 maybe if you really shop for the cheapest you can get away with.  Not sure if there is a used market out there, but you could Google for it and look for names like Traxxas, Tamiya and Duratrax in electrics.  I'm not as familiar with the Nitro stuff.

A good place to look for prices and such would be Tower Hobbies.  There are many others, but that's one of the biggest that comes to mind.  A nice local shop is Greenfield Hobby.  

Just use Tommy. I hear he likes balloons and if he takes a hit he can patch himself up.

Look online at Towers site for that Traxxas  RTR Stampede with ESC.   I think they are just over $150 and should be good for your intended use.

I also know the owner of Greenfield News and Hobby.  Let me know if you need any help.  I have a *cough* few Remote controlled vehicles but nothing that I would want to sell for your needs.  I think mine have too much money sunk in them for racing.

Heck man...get downtown on the River trap some of those big Norwegian Wharf rats..
Tie balloons on them...just to their back legs though..put some helium in them so they
can only run on their front legs....hehehehe (just kidding though for all you PETA people out there
in helium land never ever want to hurt one of those nice plague carriers)