94 Toyota 4-Runner white smoke in exhaust

My 4runner has never had a history of overheating, or even getting close to it ever before, until now. It overheated one time, I let it cool down to drive it home (about 4 miles away). By the time I got home, the temperature had risen again. I let it cool down again, filled up the coolant, and allowed it to sit again. When I started it up again after 15 minutes, thick, white smoke was coming from the exhaust. It smelled like antifreeze. I turned it off again, and now it won't start up. What could the problem be, and how much do you think it would cost to fix?