Go through as many online sites as you can find, I can't recomend any as your in the US, but I'm sure someone will tell you a few.

Try ebay as well, although if your new to RC i'd avoid secondhand trucks simply because you wont know what they have been through, and if it doesn't work when you get it the seller may try and lie to you saying your doing something wrong to avoid getting caught. I am not saying everyone on ebay scams people, but there are enough of them about to make it a bit dodgy till you know what your doing!

What are you going to use the truck for? Bashing, racing, road or dirt? there are some really knowledgable people on this site and they will all recomend something different, but if they know what your going to be using it for they should be abel to point you in the right direction.