For $200 you are looking at a used 1/10 in good shape (and maybe brushless), or a very used 1/8 in mediocre shape with a brushed motor.
Craigslist and ebay auctions are your best bet. Craigslist you will find good deals but have much more limited options.
Common choices under 200:
stampede - small, tough, lots of upgrades available
emaxx 3905 or 3906 - huge, brushed, every part upgradeable, not very tough in stock form.
ECX Ruckus 2wd - cheap, large, very tough, limited upgrades available but doesnt need anything other than metal gears.
lots of nitro are available at that price range. I just sold a working savage nitro for 135.
Depending on the surface you plan on running you might be better off with a 1/8 buggy instead of a monster truck. You can find used brushless 1/8 buggies for 200ish. Im selling my old ofna lx comp conversion tonight for 200, so there are deals out there.